Hey - I would send you a msg but I can't. I have the same username in the other place though.
I think mine is the prototype for the mono blocks, that's my guess, it's a dual mono stereo amp which is the only one made, and it was made just before the rsr came out.
It was far from Uber expensive which is why I grabbed it even though I diy - I like to remind myself what the best sounds like. And boy did it make me understand what real clarity, real "see through" sounds like.
Btw, there is a solution that would allow you to keep the au pre - you could add an upgraded volume control in a separate box. Would run you probably almost a grand but would also likely improve your sound quality noticeably.