Is there a physical space limitation that the single amp can fit?
If the Spectron and the DNA didn't do it for you I don't expect the Pass to light your fire. It is clean and controlling, but does not have finesse in the upper regions or deep bass. And it's damn large to handle!!

I've been intrigued by MacINtosh amps, but they too, are behemoths to handle.
There are lots of folks who buy the krells and say they are strong in the bass area and decent everywhere else.
I like the CR recommendation, but could you unload it if you don't like it?
I'd like to see you try the Electrocompaniets I never got to try but they are monos.

I've tried the AVA and didn't care for them. After 5 minutes of trial it was pulled out.
You might be more picky than me, but the Wyreds are decent. Too bad they don't offer a trial period. I know D-Sonic gives you 20 or 30 days Satisfaction Guarantee. But they're wired differently than the Wyreds. YOu could bi-amp with 4 Wyreds and still take up less space than the Pass!
Here's a big Krell: http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1230295908&/Krell-350Mcx