On Utopik - Linn's Latest SMPS Power Supply Reviewed

Linn power supplies have evolved over the years, sometimes quietly, sometimes with much fanfare.

Its a bit tricky to say precisely when Linn started to adopt Switched Mode Power Supplies (SMPS) - but it was during the LK era and they appeared in products such as the Kairn pre-amp and Tunebox active crossover.  Initially (and, of course modestly) they were branded as Brilliant, then Slimline, then they were just a PS in a product, gradually adopted across pretty much the full range of Majik, Akurate and Klimax units - pre-amps, streamers, turntable power supplies and power amps.  Until around 2009 these PSUs were pretty much anonymous, but then Linn made a big fuss about a new generation of SMPS - the Dynamik.

This was gradually rolled out across the then current range of products but, crucially, it was also available as a replacement unit across that same product range.  Mostly as a drop-in replacement in Majik and Akurate products, sometimes as a drop-in, sometimes as a return-to-base-for-machining process within the Klimax range.  There was much fanfare about this product but, more tellingly, almost everyone who heard the difference opted for the upgrade.  Linn provided a sticker for the bottom panel of your kit and a new 5 year warranty for the power supply.  It was a big success and probably made a nice contribution to Linn's bottom line.

But hey, a manufacturer offering to make an upgrade available to existing customers is definitely something to be praised.  So many other manufacturers expect you to ditch your existing, perfectly good, equipment and buy a whole brand new box.  I hope Linn continue this service for many years to come.

Which bring us to the (u)topic of this post.  Linn's latest power supply upgrade - the Utopik - was introduced in late 2022, starting with the Selekt (now Selekt Classic) modular streamer / pre-amp / DAC / processor / power amp unit.  Soon it was available for the "next generation" top of the range Klimax DSM/3 then gradually rolled out across the rest of the non-power amplifier products, including integrated loudspeakers, streamers, pre-amps and Akurate level Exaktbox processor / DAC units. I added Utopik to my Klimax System Hub streamer / pre-amp a couple of years ago and thought the improvement worthwhile rather than revolutionary.  That unit is, of course, digital only, do it was almost a surprise to hear any improvement, but there it was for all (who have heard it) to hear.  There are some customers who say they think that it is a bigger upgrade than the Organik DAC, but that's not my perception having heard the 2 separate upgrades in the Klimax DSM which is a streamer, pre-amp and DAC.

So what have Linn got to say for themselves about the Utopik power supply?

Well, here's the blurb, sourced from Ripcaster.co.uk - a Linn Dealer:

"Utopik - the all-new generation of exceptionally efficient and highly responsive Linn switch-mode power supplies.  This exceptionally efficient, highly responsive, and precision-regulated power supply design is Linn's first entirely new topology since 2009. Multiple feedback loops measure output versus input at each stage of the power supply, and persistently filter out mains-borne noise and eliminate 50Hz hum, even at extreme volumes.  Featuring intelligent Valley Switching, Power Factor Correction, and with precision-regulated and isolated power rails – these power supplies are Linn's cleanest and best yet.

Power is nothing without control:  Multiple feedback loops measure output versus input in each stage of the power supply, and persistently filter out mains-borne noise and 50Hz hum, even at extreme volumes. The sophisticated control mechanism at Utopik’s heart is optimised for handling between 90-250Hz mains supply, ensuring that it performs perfectly anywhere in the world without compromise. Utopik is electrically cleaner, and more efficient at higher power than any power supply we’ve ever made. Of course, this is better for the environment and saves on your electricity bill, but efficiency is also a reliable measure of how well a power supply is performing – as energy isn’t being lost as heat or noise. If you improve efficiency, you improve electrical cleanliness.

Intelligent Valley Switching: Utopik is an extremely sophisticated switch-mode power supply. In a sub-optimal switch mode power supply, you have no control over where in the input voltage waveform the switch turns off or on. It would switch anywhere, and randomised noise is generated. With Utopik however, we monitor oscillation at the transformer’s input, and look out for the lowest troughs in the voltage – a technique named Valley Switching. Utopik only throws the switch when at the floor of one of these valleys. With intelligent monitoring and control, we’re therefore keeping voltage as close to the ideal 0V when switching, resulting in dramatically reduced switching noise.

Precision-regulated Rails: Utopik has separate layers of precise regulation on its four power rails. Each has its own feedback loop, so that it is separately controlled, managed and isolated. This improves isolation between the relatively noisy digital power rail – with processors sporadically computing packets of data – and the analogue rails which feed components more sensitive to power fluctuations. Whatever the current demand of any aspect of the whole product, the remaining rails are unflinching.

Power Factor Correction: Switch-mode power supplies are common in modern technology. When in operation, each one of these is intermittently taking short gulps of current from the mains – acute spikes in current draw – which introduces mains-borne noise that affects other products on the grid by producing harmonics in the supply. Utopik modifies its current draw to be proportional to the voltage, and spreads it out over the length of the AC waveform. Instead of taking short gulps, the current draw is spread out to be more consistent over the length of the waveform. This is called Power Factor Correction – and by implementing it in Utopik, we can ensure that the product it’s powering isn’t introducing any distortion to the mains supply in the room, the building, and beyond.

Power Factor Correction is yet another technology in the power supply chain that regulates voltage and ensures that no ripples get through to the output stage of the product as a whole.  

Delivering the cleanest possible power to the rest of the chain. Utopik presents a consistent 400V output – anywhere in the world – regardless of mains supply quality."

So there you go. A lot of claims, although to look at, it's physically very similar to Dynamik.  Some comment on its switching frequency being much lower on Utopik to explain its performance, but I'm not sufficiently knowledgable to confirm or deny this speculation.

At the time of writing, Utopik can be added to the following Linn products:

Klimax DS (all models)

Klimax DSM (all models)

Klimax Renew DS

Klimax System Hub (all models)

Machined Radikal (original, /1, /2)

Klimax Exaktbox

Selekt DSM (all models)

Akurate DS (all models)

Akurate DSM (all models)

Akurate Exaktbox-6 and -10

Akurate Kontrol (all models)

Akurate CD

Kustom DSM Z4 and Z8

Majik DS (all models)

Unidisk (all models)

Two Versions

There is a physically larger version of Utopik that was released first, then there is the Utopik Miniline (the marketing term, as can be seen above, slimline seems to have made it onto the circuit board labelling).  The standard product is available in versions of Selekt and Akurate products and for the Klimax DSM/3.  The older, and physically much slimmer, Klimax products seem to have to make do with the Miniline version.  As there is only one choice to fit the product you might own, there's no way to directly compare the performance of each version against each other. Most new products have Utopik onboard from their release date - examples being Selekt Edition, Klimax Exaktbox/3 and Klimax Solo 500 and Solo 800.  Although the integrated top of the pile 360 loudspeaker is a very recent product, Linn are a little cagey about if it has Utopik or not - there's a fair chance that it is a hybrid product from a PSU point of view, perhaps having Utopik for the lower current areas such as the DACs, and Dynamik for the power amps.  But this is purely me speculating.

Klimax Exaktbox

As mentioned previously, Utopik for the streamer / pre-amp Klimax products, such as Klimax DSM, were released early in the Utopik product life.  Those with Klimax Exaktboxes have had to wait just over 3 years to see the retro-fit become an option. Even though it is the Miniline version of the PSU that comes to Exaktbox, its still necessary for a Linn dealer to send the unit back to the factory for some internal machining and the installation of the Utopik.  My UK domiciled unit was away for about 10 days, which is a very decent turnaround.  The PSU upgrade comes with a new 5 year warranty.

Just briefly - Exaktbox is Linn's proprietary multi-channel processor / DAC.  It takes an Exaktlink feed from a Linn digital streamer / pre-amp and does lots of stuff to do with phase correction, time alignment and loudspeaker crossover requirements.  Its a 6-channel box so is good for up to 6 loudspeaker drivers in mono or 3 loudspeaker drivers in stereo.  Its output is fed to multiple power amplifier channels (one channel per speaker driver) and on to speakers which have had their internal passive crossovers by-passed or removed.  Of course nearly all Linn speakers are supported with this digital approach to active crossovers, as are many others from third party provider speakerfilters.

Installed

For your investment, unlike with the Utopik upgrade to the Klimax System Hub, Linn provide you with a sticker for the underside of the Exaktbox to show the upgrade has been installed.  When the unit comes back from the factory (it has to go back there as the internals need to be machined to accommodate the new PSU) a "Utopik" sticker is provided in the box - it also includes the serial number of the Exaktbox.  Its good that this is provided, but its not an ideal solution - the sticker is too shallow and too long to go over the existing "Powered by Linn Dynamik" logo on the base panel, and a bit clumsy looking to sit underneath the existing serial number information.  I guess its generic and not specific to the Exaktbox, but that's a bit disappointing at this price. I opted to squeeze it in under the serial number.

Context

Here's the system context of this review:

Sources: CD rips and 24 bit downloads from Minim Server on Melco N1Z / Qobuz streaming service

The Chord Company Sarum-T ethernet cable

Streamer / pre-amp: Linn Klimax System Hub/0 fitted with Utopik PSU

Meicord Cat 6 Exaktlink

Processor / DACs with analogue outputs: Linn Klimax Exaktbox/2 which has the Organik R2R ladder DAC and a Dynamik PSU - this is the item to which the Utopik power supply has been added. This is has the crossovers from speakerfilters installed for the PMC Fact.12 loudspeakers.

Linn Silver analogue interconnects

3x Lejonklou Tundra Stereo 2.5 power amplifiers

Naim SuperLumina loudspeaker cables

PMC fact.12 loudspeakers on Iso Acoustics Gaia feet

Puritan Audio mains cables

Quadraspire Evo racks with Mission / Cyrus Isoplats

Listening Notes

I ran the system for about 10 hours before I started to do any listening.  I've no idea if Utopik is considered as needing to be "burned in" but I thought I'd give it some time anyway.  At the time of writing the system has been played for around 30 hours - I can't say I've heard any variation over that time period, but obviously can't say that none will happen in the future.  Many, of course, say that there's no such thing as burn-in...

Thoughts here are directly related to how the system sounded when the Exaktbox was powered by Dynamik, they're not intended to be absolutes.

Like Utopik for the Klimax System Hub streamer / pre-amp, the first thing to notice is yet another drop in what's going on in the negative parts of the music and the gaps between the music.  Yep, a tiny layer of noise has gone - and its a weird one because (like an extremely well set up subwoofer), you don't notice it until its not there.  I'd say this was a bigger change to this aspect than the PSU made inside the streamer.

Secondly, it seems that the music has picked up in pace.  Of course it hasn't, because the track still plays for the same length of time, but there is a little more urgency - I would guess this has something to do with the reproduction of transients of each new note - presumably there's a little bit less time lag for them to happen.  Thankfully this has been achieved without any sign of aggression nor harshness, which is the danger with systems that "crack along".  Its a welcome change, not one that should put you off if you like a more laid back kind of presentation - this isn't like a change between warm valves and analytical digital which can be presented as edginess, its just what feels like a timing improvement.

The main change, for me, is in the way that the music interacts with itself, if that makes any sense.

An example is Submotion Orchestra's "Prism" (from "Kites" on SMO Recordings) starts with Wood's floaty vocals underpinned by strings - after about 1m 30s the bass line kicks in.  Now this sudden contrast feels greater, the emotional change has more impact, the contrast between voice and backing is greater. Then as the vocals and bass line work more closely together you get a real feel for a collaborative effort building the crescendo across the rest of the track.  

On Tash Sultana's "Kiss the Sky" (from "Return to the Roots" on Lonely Lands Records) the lilting dubby background flows more convincingly, the kick drum effect has more thump, the initial cymbal crash has more impact and startles that bit more than before. Its an interesting contrast between the crispness of the rimshot, the brass and the flowing easy going nature of the under-currents.  The shimmering guitar part towards the end of the track really adds more lift to the song and makes me wish for a longer version to continue the experience. Overall the track is more fun to listen to and I get into the groove straight away.

Malia and Boris Blank's "Smoldering Ashes" (from "Convergence" on Universal) starts with a tom tom type drum pattern.  Previously this was easy to follow in terms of the pattern and the indivdual drum sounds but now it bounces along which gives a more jaunty feel - the toms that have a bass under pinning them have more punch and drama.  This track is full of tension but the short punctuations of minor chords, using various different instruments, really add more impact and shades of intrigue. The drum pattern is easier to follow through the whole track. 

Bonobo adds a few clicks and twists to the beginning of the track "Brambro Koyo Ganda (featuring Innov Gnawa)"  (from "Migration" on Ninja Tune). They might seem a bit superfluous, but actually they weave in and out of the whole track. This weaving in and out is now more relevant and tends to help tie the intro into the whole track.  Then there's that bass line - now more punchy, more purposeful and again there's that new ability to drive the track along with more energy but without more aggression.

To find out how an improvement to the presentation of individuals and instruments improves with this PSU, Michael Kiwanuka's recent track "The Rest of Me" (from "Small Changes" on Polydor) is a good example. The resonance qualities of the opening acoustic guitar are richer, more nuanced and add to the feel good factor right from the off.  The cymbals are shimmering, adding to the good feeling, not clashing nor jarring - they're full of subtle complexity.  The bass guitar, like the Malia track, bounces along to add feeling and groove.

To summarise, this PSU will give you more of a feel for the rhythm of the music, the contrasts, the emotions and the complexities.  If it is value for money, or not, is a personal choice.  For me its not far off the improvement that the Organik DAC brought to the musical experience.  More believable, more engaging.

Now, just one more track...

A "New" Retro Streamer - Pushing the LK Envelope

For information only: this post is not a set of instructions nor is it intended to encourage any kind of modification of electrical products. As they say: "Do not try this at home".

Some of you may have read through the first "episode" of what has now started to be a theme - modernise a Linn LK enclosure with a streamer, or, from the other perspective, taking a modern streamer down the retro route.

That little excursion is available here. It covers off the history of the LK boxes and describes the Sneaky Music DS also used in this project.

A quick recap - that story covers converting an example of the iconic Linn "LK" enclosure into a streamer as purely a source component, using a Linn Sneaky Music DS in "source only" mode.  That's possible in a non-ventilated case, but to use the full features of a Sneaky, including the power amplifiers, that needs a ventilated case, so something from the all-in-one or the power amp sections of the LK range of products.

The other difference is that in the previous project I wanted to present only the source component connections to the outside World, but with this project the intent is to provide all of the Sneaky's connectivity so all of its functions can be enjoyed. Let's see how it panned out..

Basics

Ingredients this time:

- Linn Sneaky Music DS

- Linn LK85 Power Amplifier (with dead mainboard)

- Lots of M3 fasteners

Plan

- Strip the interior out of the LK85

- Trial fit the Sneaky MDS board and PSU

- Work out all the fittings etc., similar to the previous project

Did That Happen?

No. And, yes.

Starting with the LK85, which had a dead mainboard, all the innards were removed - as it happens the LK85 toroidal transformer was repurposed into an LK140 power amp that had a healthy mainboard but a dead transformer.  So the LK140 won't produce the power it used to, but its back up and running and can be used again.

The LK85 chassis stripped bare looks like this:

The back connector panel is at the top of the image, the toroidal transformer mounting hole is midway down on the right then the ventilation and substantial heatsinks.

The ventilation and heatsinking on the LK85 and give confidence that the comparatively low power amps in the Sneaky Music DS will be adequately cooled.  Next it was time to remove the heatsink from the base of the LK chassis - this involves drilling out the securing rivets.

Drilling out the heatsink rivets

This left lots of space to work in side the chassis but also a base plate that wasn't particularly secure.  So once the heatsink was out its mounting holes, that also mate to a centre strengthening plate, were replaced with M3 nuts and countersunk bolts.

Countersunk bolts replacing the heatsink rivets

So that's the basic starting point.  Time to have a look at how to layout the Sneaky boards inside the LK chassis, which is likely to be different to the previous project because there's now the need to look after the power amp and it's heat production.

And then something struck me - once the Sneaky MDS is relieved of its clamshell outer panels, the remaining chassis looked very similar in width to the LK.  If all went well, perhaps the whole Sneaky chassis would slide down into the LK with no modification? A quick check and I found that it is EXACTLY the same width as the LK - so no, it won't slide in easily.  Because the LK box has a chassis with sides and then the top / side panels are a slide over clamshell, the internal side walls are not visible on a fully assembled product. A few measurements told me that it would be possible to cut away sections of the chassis side panels and integrate the entire Sneaky MDS into the LK rear panel - so no need to strip the Sneaky boards / PSU and no need to use jumper cables from those boards to a custom back panel.

Cutting away the side and rear panels ready to accept the Sneaky MDS chassis in its entirety. Around 3/4 of the length of the side panel has been removed.

Trial fitting of the whole Sneaky MDS chassis into the newly cutaway LK inner panels.

In the above picture you can see that the external width of the Sneak MDS is exactly the same width as the LK chassis and in this trial fit, this was confirmed.  The 4x threaded bosses in the top of Sneaky chassis are the mountings for the external clamshell panel.  They are replicated on the underside and their positioning means that only 4x standoffs can be mated to them to supply support and fixing in to the LK. Plus the height up from the LK base means no need to powerfile away the LK's old threaded bosses, so one less job to do.

I didn't have standoffs of quite the right length to screw directly into the Sneaky chassis, but adding an nut to the threaded section before mating them up gave exactly the right clearance.

Making the standoffs in stock a couple of millimetres taller

Threaded standoffs fitted into the Sneaky threaded bosses that normally provide a fixing point for the outer clamshell panels

Underside of the Sneaky chassis with standoffs in place

4x holes were drilled to align in the LK chassis and another trial fitting undertaken. Note that the front to back location of the Sneaky chassis aligned the original back panels of both products.

Alignment of the remains of the LK rear panel (along the bottom of the picture) with the entirety of the unmodified Sneaky rear panel. Together they don't vertically add up to the same total of the old LK back panel, leaving a gap across the whole width

The only modifications needed to the Sneaky are two fold.  First, and easiest to describe, is swapping the original front blue panel LED to the green "power" LED next to the on-off switch of the LK.  This just involved a swap of the connector (as per the previous project) and re-routing of the cable.  The second part was to accommodate using the front power switch.  This required a slight tweak - the brown positive cable from the IEC rear panel socket that goes directly to the PSU was unsoldered and effectively routed round to the power switch on the front before going back to the PSU. Handily, by fitting a rubber grommet around the Sneaky's front LED mounting hole, it was possible to route this cable without and modifications to the Sneaky chassis.

The LK power switch assembly as removed from the amp.  The IEC socket is cut off leaving the 2x brown cables going to the switch

This is the Sneaky front LED mounting point.  A rubber grommet protects cables passing through - this was used for the mains switch cable and the LK green front panel LED

Front panel switch fitted with a 2 pin connector

The redirected brown cable is sleeved and makes its way neatly under the PSU output cable off to the front panel power switch

Passing out of the Sneaky chassis to the front panel

Adding a 2 pin connector to mate up with the connector added to the front panel switch leads

And that's about it. Except for that gap across the top of the rear panel.  The material for this was taken from the top of the original LK back panel, but mounting needed to be resolved.  Handily some offcuts of aluminium panel from the last project were just the right width to create a pair of mounting brackets.  These were cut to length, bent to shape and bonded to the back panel gap filler. They then sit neatly onto the Sneaky's upper clamshell mounting points.

Offcuts cut to size for their new role

Offcuts bent into brackets

Bonding the newly fabricated brackets to the newly created back panel filler panel. Note use of universal clamping equipment

And that was largely that.  Some primer and matt black spray paints finished off the exposed LK chassis edges and spruced up the rear panel.  I used satin black on the first of these projects and gave matt black a try here.  I will keep to the satin for future project.

So here it is, the second of the LK streamer projects.  This was a simpler build than the previous one and is probably the route I'd use again in the future.  It has the benefit of exposing all the functions of the Sneaky but it has the downsides of needing a vented enclosure (harder to get hold of because the amps are probably mostly still in use) and it doesn't have that more bespoke feel to it. There is one further advantage - the Sneaky needs the absolute minimum of changes, so could be converted back to standard in about 15 minutes.

Rear filler panel mounts

Finished

LED and mains switch cables pass through the grommeted LED hole of the Sneaky. Connector of the power switch cable

A neat final result

Base panel labelled up with the new information.  LK mains transformer mounting hole plugged with a rubber bung

As per the plan - absolutely no clue that this is anything other than an LK power amplifier

Until you turn it around and find a whole bunch of unexpected connectors.  As you can see in this picture the top filler panel, the unmodified Sneaky back panel and the remaining lower edge of the LK back panel marry up well to make an (almost) seamless result.

And finally...

Here is the Sneaky going through its boot up sequence, using the original green LK LED rather than its own blue LED.

A Retro Streamer, Is That A Thing? Linn's Iconic LK Series Brought Up To Date

For information only: this post is not a set of instructions nor is it intended to encourage any kind of modification of electrical products. As they say: "Do not try this at home".

Boxing Clever?

Back in 2007, Linn introduced the Klimax DS streamer and told the World that they believed streaming to be the future and that it outperformed their best CD player at that time (the CD12).  They also cemented the format of the new Klimax casework introduced earlier with the Klimax Solo power amp and the Klimax Kontrol pre-amp.

Klimax DS

With the full rollout of the lower Akurate and Majik ranges, Linn's iconic LK casework from the 1980s into the 2000s was fully retired.

Akurate DS

The LK range really span the whole of Linn's electronics product line with its origins in 1985 with the first pre-amp and power amp, the LK1 and LK2, right up to the 2000s.  The casework for those early components were product specific but they set the basic blueprint for what became the "standard" LK box - a 2/3rds width box when compared to most hifi of the time.

Some LK product examples:

LK2 and LK1

Linn Classik all-in-one system

Linn Klout power amplifier

To complete the history lesson in the context of this post, all streamers after the 2007 Klimax DS have been in Klimax, Akurate or Majik casework, plus some more specialist products such as the Sneaky MDS for multi-room installs and the "lifestyle" Kiko all-in-one product.

Some Linnies lamented the end of the LK casework, seeing it as a simple iconic design which embodied musicality over bling.

So, is there a way of building a streamer that will give that "retro" LK style but updated with more recent internals?

Basics?

Linn's later range of cases are, generally speaking, larger than the LK range.  Although the internals of the Klimax casework, which is machined from a solid billet of aluminum, is not very spacious.  Maybe there is a later project on that topic...

This means that something more compact needs to be sourced to form the basis of a streamer inside an LK case.  LK cases need to be sourced too, which is easy if you want to dismantle a working product (and pay the prices of working products), but very much harder when you look for dead products to use - Linn's equipment being so reliable, even many 30 year old products are still working well. Sources of cases are very welcome - please add to the comments below!

As mentioned above, there is the Linn range of streamers that are built primarily for multi-room installations.  The intro level is the Sneaky Music DS (now discontinued in favour of the multi-zone Kustom DSM product) which is a streamer and amplifier in one (it is not an all-in-one product as it does not have the ability to accept other sources into its pre-amp).  It is housed in a very simple clamshell style case around a rigid chassis.  8x screws open up the case and reveal the innards.

I already use a Sneaky Music DS in the workshop system, lightly customised (or kustomised?).

Workshop Music DS

A Good Fit?

So, does a Sneaky Music DS fit inside a standard Linn LK box?

No, the basic chassis is too wide.

What might've been a day's project therefore become more involved.  It started with stripping the internals of the existing LK box and removing the main circuit board and PSU from the Sneaky (the IR board came later). 

Inside of Sneaky Music DS before dismantling

The empty Sneaky Music DS chassis (IR board still in place, top right)

Then, several orientations / positions of the circuit board and PSU were considered - primary focus being on ensuring existing mains electrical safety is maintained, the second on minimising change.  Several things needed to be taken into account on the orientation decision:

• Electrical safety
• Ease of extending the connections from the board to the back panel
• Closeness of audio circuits to the power supply
• Where mounting points need to be drilled into the LK chassis
• Room for the first stage heatsink
• Minimising cable changes for the power supply
• Ensuring the power supply heatsink makes good contact with the enclosure

You can see the final orientation chosen in the later pictures.

I also wanted this first project to be purely a DS, rather than the full Sneaky Music DS with an amplifier - to think about this as a source, rather than an amplified room solution. It would therefore fit better into a existing LK based system as a new source format.

The Sneaky case has slots in the top and bottom to allow cooling of the power amplifier modules which have their own heatsink.  That would mean the LK case would need to be a vented version too - I didn't want to go down that route on this project.

A search through the settings options on Linndocs - and the impact of those settings - established that the "volume control off" setting also disabled the power amplifier - resulting in minimal heat production.  So this solution has to be configured that way in Konfig or in the online Manage Systems tool - I left the most immediate heatsink attached to the power amplifier chips and it is connected to the casing using metallic mounts, so if there is any residual heat it will be dealt with.

So a DS it would be then.  This had another couple of implications - a need for a new, custom, back connector panel (omitting the speaker terminals and the old skool Linn multi-room system connections) and the ability to leave the donor Sneaky Music DS chassis in one piece - enabling the boards and PSU to be transferred back there if required in the future.

Quick Build?

In general terms, this process lead to a fairly straightforward build.  Mechanically the existing LK rear panel needed to be cut away and replaced by a custom version, but electrically I needed to find a way to transfer the required ports (ethernet, audio out, SPDIF out, Toslink out etc.) to the rear panel, in addition to a "fallback" facility.  In previous projects I've attempted to remove an external connector (such as audio out) from a circuit board to be replaced by cables, I found it far too easy to damage the delicate tracks on the circuit board this way.  So "jumper" cables looked to be the best option. Although this looked simple enough, sourcing suitable cables took a while to find and then to be delivered. Then some needed some further modification...

• For Toslink I found a "pass through" panel connector that has mounts and female connectors on both sides - combine this with a short optical cable (one end having a swivel 90 deg mount) solved that one.  (in the later pictures this is the braided silvery grey cable)
• I wanted to be a bit flexible on the route for audio out so chose a pair of standard interconnects with 90 deg connectors each end - then cut off one end of this cable so it can be soldered to a panel mount pair of phono sockets on the back panel.
• Mains was easy - the existing LK rear panel socket remains as does the front panel switch and the existing connector is directly compatible with the Sneaky power supply.  The front panel LED "on" indicator we'll get to soon.
• SPDIF - I chose a panel mount single phono socket.  However, in the Sneaky its outer connection has no electrical connection to the Sneaky chassis - so I needed to find a nylon external washer and a nylon "stepped" T washer internally where the leg of the T goes around the phono socket and through the back panel to create electrical isolation.  The correct depth of T couldn't be found anywhere so I purchased something too long then filed it down to size.  The connection from the Sneaky board SPDIF to the new external connector was a simple shortened phono cable.
• Fallback - this is a tiny microswitch on the circuit board. Fortunately it has dual orientation mounting which means there are 2x tabs on the top of the switch that replicate the bottom connections.  Cables soldered to these tabs are taken to a stainless steel push switch - another component that had to be ordered specifically for the project.
• Finally - ethernet.  After much searching I found a very short cable that has a normal RJ45 plug on one end (to plug into the Sneaky board) and a chassis mount socket on the other end.

So with all the connections sorted, the build got underway, trial fits and test power-ups continue throughout the project:

The first modification was to remove all the existing threaded mounting bosses in the LK chassis that would not be used and would be hidden under the circuit board - short circuits are not a good idea.  I left the bosses in other areas in case they could be used for cable tidying clips.  A power file made light work of this job.  The positions of all the original Sneaky circuit board mounting points were also marked up and 4mm holes drilled through (the screws are 3mm, but 4mm allows a little "tolerance").

LK bare chassis - black dots are for 4mm holes, arrows for bosses that need to be filed away.

LK chassis with bosses removed and Sneaky board mounting holes drilled

Closer view of removed bosses.

The power supply location was then addressed - drilling through the side of the LK chassis and countersinking to allow the top sleeve to still slide over the main chassis without fouling on screw heads.  Also, because the power supply unit is in a different orientation with more space around it, a angle strip of aluminium was bonded to the side wall to ensure good locating.  

A small amount of countersinking on the underside - note the need to relocate one of the feet by about 2mm

Countersunk hole in side panel for PSU mounting

I didn't want to drill the front panel of the LK box, keeping it as clean and traditional as possible.  So a hole is cut into the front edge of the base panel for the IR receiver - not sure how well this will receive a signal, so will see how that goes.  Also to keep the front panel clean, the existing green "power on" LED is re-purposed to function as the original blue status LED that's provided on the Sneaky.  The connectors used by Linn are not branded and I have not been able to track down the correct product.  However, an existing common industry connector has the correct pin spacing and a little work with the powerfile on the outer dimensions of the plug ensures a good fit.

Modified connector

Connecting the green "power" LED to the Sneaky LED port

Hole for IR sensor - it sits on its own very small daughter board

Additionally M3 10mm standoffs are added to the underside of the Sneaky circuit board. These align to the new holes in the base of the LK chassis and are secured using black dome headed M3 allen bolts from underneath.

M3x 10mm standoffs. This is an early trial fit - completed project has shakeproof washers between the nut and the circuit board

The final element is to address the rear panel.  A connector layout was sorted on paper then the plan for cutting out the existing rear panel marked up - for strength of the existing chassis and to support the new rear panel, cutting is kept to a minimum.  The rear panel is formed from a new sheet of aluminium then the holes drilled or cut out with a jigsaw, checking dimensions and fit iteratively.

Rear panel cutaway, retaining as much as possible for strength and to support new rear panel

One of the many trial fittings of the new rear panel. In this photo you can also see the aluminium angle strip bonded to the side panel - this helps with locating the PSU.
Random selection of isolating plastic washers on hand.  Of course, as usual, the exact size of washer for the SPDIF connector was not available, until Amazon delivered the solution...

And Finally?

Finally? Well, these things are often revisited later. But for now we have a fully working DS as a source in an LK box, so mission accomplished.  Finishing touches included several coats of spray satin black paint for the rear panel and labelling from a Brother label printer.

There may be follow ups, perhaps a fully functioning Sneaky Music DS with the amplifier in play too.  Perhaps something completely different!

Please leave any comments / questions below, and thanks for reading.