A Knekt Roomamp came up on ebay recently. It was described as "in very good condition, but not tested". So I put in a silly bid and left the software to its automated bidding process.
A few days later the amp was mine and just turned up yesterday. Using the "audio out" sockets as the audio input (as described in a thread on here somewhere) I hooked it up to a source and gave it a whirl. Well, it works fine and does a reasonably good job.
In a system consisting of:
Chord Prodac Pro Gold
Musical Fidelity V-DAC
I used the volume control in the Touch and compared the Roomamp against the power amp sections of an original NAD 3020 and a much more recent Cyrus 6 integrated amp. My conclusion is that the Roomamp power amp sits roughly mid-way between these products in terms of sound quality. Sharper and more detailed than the warm NAD, not as solid, refined nor bass deep as either the NAD nor the Cyrus. However, I did think that it is a touch bright and metallic with cymbals (at least into the Missions) compared to the other amps. In fact, it was a rather sterile kind of sound - I really found it difficult to decide if it was more or less musical than the NAD - their presentations are very different, but I found myself more inclined to enjoy the NAD's warmth and musicality. Overall, the Cyrus walked it, but then it should given how recent it is and how much it would cost new.
However, if you're looking for an office / study system driven by (for example) Spotify on your computer, or a bedroom system driven by a Squeezebox then the Roomamp does a pretty good job.
And if you're willing to take a bit of a risk on "untested" then you too can enjoy a Linn power amp for as little as £33.35!