I will disagree with most, and agree with Wadia150. First of all, it is hard to find an amp that is smoother in the mids and sweeter on the top than the "sleeper" (of a Pass amp), the Adcom 545. Ahhh.. read the ba-zillion consumer reviews in audioreview.com if you don't beleive me. The problem exists in your NAD pre-amp, the 555 and ~perhaps~ your cables. The 545 Adcom is not the Holy Grail for transparency, nor is it layered in it's depth,... BUT "open", "strong" and "sweetly detailed" it IS. I have reservations (imho) about the Adcom 555. It is nasty, dry and can bite little chunks out of you. I don't like it. It is mearly a 545 on cheap back alley steroids. It has enough of them in it to make itself sick and ill tempered. It has collapsed it's own soundstage, dropped it's depth into an burning abyss and pushed it's evil manables into a room full of hot coals. Whoever is left to suffer along with it will scratch at their ears like mite infested felines. Get rid of it. As someone else suggested, perhaps try the 545 by it's lonely ole' self for a short while. Think of crossing at a lower freq. and perhaps with another cheap, but "grip"-heavy amp... Parasound, lower-end Bryston.
My vote is for a ride out the window for the NAD followed by the 555 tied to a cinder block.
Tubby
My vote is for a ride out the window for the NAD followed by the 555 tied to a cinder block.
Tubby