UGS adventures

As usual I am (very!) late to the party... I am trying to understand how the UGS circuit works, and it seems I need a little help. Is there an explanation somewhere (in this thread or elsewhere)? I would be glad for some pointers.
If you would care to read even the last couple of postings, you would find all relevant links and infos.
Like 1351 or 1354... and I would check everything else as well.
 
I am not quite sure, but these posts seem to relate to the firmware and other "externals" of the UGS+Muses preamp from thd group buy. However I am looking for a rundown how the UGS circuit works. I am sure it's out there, but this thread is very long and it's hard to find things (the same applies to the GB thread , and also to the other thread in the French forum).
 
I have finally finished my UGS preamp! It sounds fantastic and I'm very happy! I do have a question though, the volume seems to "jump" at a certain level... When I reach I think -23db it goes a little quieter and the volume changes very little but at around -17 it jumps up and goes much louder.
I first thought I had soldered the wrong resistors but since the same thing happens in both channels I thought I should ask if someone had encountered the same?
 
^ Is this the original UGS AI version or the UGS Muse version. Since you mention the wrong resistor(s), I am assuming it is the AI version, with what I presume to be a relay based volume control scheme.
I haven't looked at the schematics for this one (AI), but I would start by looking at the processor bus to the relay controllers. Any shorted or non connected pins on what I would presume to be the data bus?