McIntosh MC601 vs Pass Labs XA 100.8 (or 160.8)

Thanks for your detailed response tjassoc. I've got a call in to Mark at Reno Hi Fi (he's in Southern Cal buying Pass products!) that I'm waiting to be returned. Can you tell me how to reach Kent English?
I live in Canada, so getting amps from Reno Hi Fi on an audition is not an option - due to fees required when the amps cross the boarder which can't be refunded. 
I've got a dedicated listening room I completed about a year ago, with in-wall wiring from JPS labs, rhodium outlets from Furutech and 3 20 amp dedicated lines (one for each amp and one for the front end equipment). My digital front end (which is mostly what I listen to) is a Meridian Sooloos system feeding a MSB Signature DAC IV (via an Audioquest Wild RCA cable) with Signature power supply which I run directly into my amps via Audioquest Sky wire. I use Stillpoint Ultra 5s under the Sashas and amps and Ultra SSs under the DAC. The room sounds good with the exception of a nasty standing wave problem between 200 hz and 50 hz, which I've mostly tamed with bass trapping room treatments. The system has been setup very carefully (over the last 10 months of agony - audionervosa is far too strong in me, I'm afraid!) and sounds very good to my ears. I'd LIKE to just listen for pleasure but end up listening "critically". Things need to be "right" before I can relax into the music (which I can mostly do with how it's sounding now). My goal with new amps is to increase the "musicality" of the system.  I assume I can achieve that result with Pass amps and figured I could with the Macs too but I don't want to loose any resolution, which I'm afraid I might with the Macs. 
BTW, I see that you were wanting feedback re ethernet cables.  I was playing around Audioquest ethernet cables a couple of months ago, auditioning the Forest, Cinnamon, Vodka and Diamond. In my system they made a ridiculously impressive improvement! Transparency, bass definition, sense of space and just giving a strong sense of "life" or "aliveness" (mid range presence I suppose) to vocals blew me away. I ended up buying a Diamond and a Vodka (couldn't afford two Diamonds). Performance improved with every cable in the line, as with all AQ wires, in my experience. They are a worthy investment in a high resolution system in my experience. 
If you can tell me how to reach Kent English I would love to give him a call.

So, I just want to update you regarding my search for new amplification. Thanks to Cal3713 and tjassoc for your tip on talking to Kent at Pass Labs. I did speak to him (and two other people there as well) and to Mark at Reno Hi Fi. Kent particularly was helpful. Actually he recommended either XA60.8 or the XA160.8 saying that they are both warmer than the XA100.8 and therefore would be a better match for the Wilson Sashas! I spent the last 5 days with the McIntosh 601s in my system. I must say that I was very impressed with them! They are totally different sounding amps than the MC501s, which I tried out a couple of years ago (albeit with a different front end, different cable and in a different room). I didn't like them because the high frequency range was MIA. The 601s were considerably more transparent than my Krells (and the 501s), which surprised me. They were very dynamic and produced a very strong sense of presence of the recording venue, which I was also surprised by. The highs were extended and smooth, but not overly smooth; I would describe them as somewhat "relaxed" sounding, but again, not overly so. The bass was actually more controlled than my Krell mono blocks - maybe that's their age showing. Very nice amps. I believe I could live happily with them. This of course, makes for a problem: do I buy the Pass amps (probably the 160.8s, which, BTW, Kent described as "one of the best amplifiers ever made, in my opinion" - and he didn't strike me as man prone to hyperbole!) without hearing them, risking being disappointed if I don't like them as much as the Macs. Or buy the Macs and be happy that I liked them so much and know I can be happy with them long-term. My "gut" tells me that the Pass amps do all what the Macs do but even better. (Kent mirrored  tjassoc's feelings about their ability to bring the recording venue into the room, saying the .8 series is even better at this than the .5 series. As I said, the Macs were pretty good at this too, and I found it VERY compelling!!) So, I've got some thinking to do over the next couple of days and a hard decision to make. If anyone else out there has any experience hearing these two amplification systems, I'd VERY much appreciative hearing from you.