McIntosh MC601 vs Pass Labs XA 100.8 (or 160.8)

I've lived with Pass amplifiers for a long, long time. From Nelson's Threshold days, with his Aleph amplifiers to his next to current designs.
We currently have a pair of XA-200.5's for our Sasha I speakers, MIT Oracle cables, Meridian 800 series digital components and Sound Application line conditioner.
Our room is ideally set up (if there is ever such a thing) and recreates the illusion of a live performance, especially small venues - very well.
A very neutral, natural and revealing system. It's very easy to recognize the acoustic environment the performance was recorded.
I explain so you understand the level of our system and what I'm about to say.
BTW - at this level, software - well recorded music - is critical.
Pass amplifiers are the most natural amplifiers I have found that are reasonably priced. I haven't heard the .8 series, nor have I heard Soulution, Constellation or other very expensive SS gear. The amplifier I've heard that sounds closest to the Pass amplifiers we have are the $50k D'Agostino Momentum monoblock amplifiers.
The Pass amplifiers provide the best fidelity of the recorded performance at anywhere near their price range. I could wax poetry about their strengths, but it's easier to explain by asking if you're looking to recreate the performance as it was recorded. If you are, I haven't found better anywhere near their price.
The McIntosh MC601 do not perform the same way. They sound very nice, but they homogenize things. They help bad recordings sound better because they are more forgiving and not as revealing. They don't provide the insight to great recordings and can make many recordings sound similar. If you are not as critical a listener, and want to enjoy more music that may not be recorded critically well - the McIntosh may be attractive.
Driving the Sasha Series I's.
These speakers can be difficult to drive, because their impedance dips low (somewhere in the mid-base region if I remember correctly). I've auditioned the Sasha I's with Lamm Ref 1.2's and Spectral gear - both were very good but I preferred the neutrality and organic reproduction of the Pass (Lamm's were SLIGHTLY base heavy and the Spectral equipment was SLIGHTLY dry - just MHO).
Because the Sasha I's can be a challenge, I'd recommend the 160's. Will the 100's sound good - no doubt, but the 160's will perform better not just because they'll have the extra muscle to provide the drive when the music demands it, but because each step up in the Pass amplifier line is a better amplifier, it's not just the same amplifier with more power. This was explained to me by Kent English (a WONDERFUL GENTLEMAN) and I'm sure he'd be very happy to discuss things with you and answer any of your questions - especially considering you have no local Pass dealer. I do have Pass dealers local and Kent was very insightful and generous with his time.
Mark at Reno will let you try the Pass amplifiers, and if you can - compare them side by side to the 601's (either the 100's or the 160's) using well recorded performances and you'll understand exactly what I'm referring to. 
Without trying to sound offensive, this presumes your system is at a level of performance that will reveal these differences.
Most importantly - enjoy your music! Life is too short not to listen to music that stirs our sense and moves our souls!

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.

Not a great data point for you, but I compared Mac (MC402) and Pass (XA-30.5) products much further down the line and felt the Pass was better in every way possible.  I've seen some people go the other way with a very similar comparison though.  System synergy I guess... I had Thiels at the time though, go figure.

To contact Kent (I really loved interacting with him as well, very honest information about the products), just e-mail info@passlabs.com or call their customer service number, 530.878.5350.  It's all listed on the contact page of the Pass website.