Best Tube Amp For Sonus Faber? Or Pass XA-100.5? $6-7,500 Budget, Purchasing Used.

The new IQ continuous auto bias in the latest VAC amps are a night and day difference from their prior 160, 200, 300 phi models.  Far more smoother and transparent, tighter bass, etc and more stable power output makes it a lot easier to handle all speakers.  I owned the VAC and as well as the SF Olympicas and the Elipsa and handled them fine.  the VACs are paired with Magicos, Focals, Vandersteens, Sonus Fabers, Harbeths, and know they can drive them well, even with the stock KT88s.   But if you're in love with the PASS LABS, then you it seems like you found what the sound you're after.

I have an Audio Research VM-220 that I just got checked out and put new 6550 tubes (from AR!) that I will be listing shortly.  These monos powered my Sonus wonderfully, but with 12 tubes in each, the room can get warm.  Great sound though. - PM me if interested.

I should perhaps have mentioned that a big part of originally wanting the 100.5's had to do with how impressed I was after hearing the 60.5's (not enough power for my speakers) and recalling John Atkinson's review a couple years back calling those the best amplifiers he had ever heard. As a followup, I was told that the 100.5's were essentially the 60.5's up-scaled, which doesn't seem to be the case?

All Pass amps seem to have a slightly different sonic signature. From what I understand, the XA160.5 is the next logical step up in power and flavor from the XA60.5. I've had many Pass amps, and while the highs and mids were wonderful on XA100.5, the bass seemed bloated to me. Some say it the most tube-like of the amps but, to me, not in a good way. The XA60.5 were amazing sounding amps (I love the XA60.8 and X350.8 as well). I love Pass, if you can handle the heat. My favorite right now is the X350.8. Several friends have them and I always look forward to going to see them and listen to their systems.  

djfst said:

" The new IQ continuous auto bias in the latest VAC amps are a night and day difference from their prior 160, 200, 300 phi models.  Far more smoother and transparent, tighter bass, etc and more stable power output makes it a lot easier to handle all speakers.  I owned the VAC and as well as the SF Olympicas and the Elipsa and handled them fine.  the VACs are paired with Magicos, Focals, Vandersteens, Sonus Fabers, Harbeths, and know they can drive them well, even with the stock KT88s.   But if you're in love with the PASS LABS, then you it seems like you found what the sound you're after."

The problem I'm having in moving to a Pass is size and heat. That and the fact that as joeinid noted above, the next amp up the line that shares the true greatness of the 60.5's that I like so much are the 160.5's. Those are not only huge, but can each double as a furnace, in my room, I could sell space as a sauna. Not to mention they are thousands out of my budget. 

I was considering the highly rate Pass 350.8, and one was just available at a price several thousand under the going rate, and in my budget, but it sold before I could make a final decision.

So I was strongly leaning back toward the VAC and even talked to them at length. I know the PHI 300.1 will handle my speakers perfectlY, and there is one available, but it's not the latest series which you've noted represent a "night and day difference". And the newer model PHI 300.1a, on the very rare occasion it is available for sale, used, runs in the $10k area and also out of my budget. 

Those situations currently have me in a position where there isn't a clear choice unless I go with the PHI 300.1 available at the moment, which, both you, and an audiophile friend from Chicago have advised me is decidedly lower in sound quality than the newer version.