To answer some of your questions, the room they used to be in was slightly larger (19x14). I got more bass driving them with PS Audio HCA-2 or Pass X-350, but tube is ultimately what I wanted and settled for. Listening position was also tried, but at 3' from the wall, it had worked well for me for the past several years.
Yes, two dedicated AC lines with power filter feeding CD and pre, power amps are plugged straight to the wall. No bi-wire capability with Sonus Faber, so one pair of amp is all I can use (thank God).
Sounds like wire is what I should replace? I had very good luck with JPS Superconductor 2, but they were so stiff they broke one of my input on the SF Line 3 SE. What else is out there that won't sacrifice the air/speed/transparency of Diamond X3 and still give me more bass?
Thanks.