Audio Research versus McIntosh tube amps: anyone experience or compare both?

@bobbydd since you asked a leading question, you will get answers which are obviously this or that. What you are looking for is a great sounding tube amp which has the bloom but not slow or colored. Check out Rogue Audio Stereo 100. It has everything that the Pass does well + warmth and naturalness, without any voicing. Both ARC & Mac are voiced. Rogue Stereo 100 and Apollo Monoblocks sound natural and unvoiced. They both have a triode/ultralinear switch. I always preferred the triode mode. Natural, harmonic, and transparent. Here is a review comparing Rogue Stereo 100 and Pass XA25

https://www.stereophile.com/content/rogue-audio-stereo-100-power-amplifier

@bobbydd

If you decide to try a more modern ARC, don’t get distracted by the other amps, like the REF 150. The REF 75SE would be all you need. It checks all your boxes for simple, fewer tubes and easy to bias from the faceplate. The 150 you have to remove the cage, and get your volt meter out with the probes on the board. It may not sound like that much from simply describing in a post but as a former owner of both amps it gets really old, FAST! Being able to turn the knobs on the 75 and stick the little tool in the hole is so convenient to give you the peace of mind that things are in good shape. I put the REF75SE up against a solid state Mc, the MC462 and it provided the same output and better/more musical sound. I haven’t ever heard a Mc tube amp but as others have stated, you are already an ARC fan so you owe it to yourself to try a 75SE. Get one at a good price and you can always resell if you want but I suspect you won’t sell it until you are ready to move up the ARC line to their newer auto-bias models. Have fun!!!!

I am actually somewhat surprised that you didn't like the Pass/Pulsar combo.  I had  Pulsars in my music room and to me they are a warmer speaker, which I paired with a Prima Luna DiaLogue HD tube amp.  I thought that that combo sounded very nice.  Nonetheless, I wonder if keeping the Pass and getting an ARC REF 6 preamp might be the ticket.  I have a REF 6 and a Pass 250.8 for my Wilson Sabrina X's and it really hits the spot.  Let your ears tell you what sounds best!

Most definitely the ARC, but you were on the right track with the XA25... Why is the obvious answer a tube amp? 
A really good option, and one I ran with big B&W's... ARC Pre, big Pass amp! I used an X250.5 at the time, but if you want tube like sound as opposed to intense focused bass, crystal clear mid & hi's.... Big mono XA's!
XA60.8's will sound completely different than your XA25
$14K a pair new... there are 3 year 0% interest deals out there...

I bought an Arc REF75 so long ago I cannot remember, sent it to ARC and had it upgraded to REF75se another long time ago.  I have never had the thought to ever change amps, I am pretty sure this is endgame for me.  A year ago it started sounding muddy in the bass and lost detail, checked the hours, 2030 on those power tubes.  Put in new tubes (from ARC, yeah, reluctantly paid the price) sounded much better immediately, now 80 hours in it sounds wonderful again and I know it is just starting to bloom, in another 200 hours, back to audio bliss.  Pairs perfectly with my ARC REF6.  After reading reviews and talking to people I am feeling I will prefer the REF6 sound to the REEF6se sound though that is a somewhat baseless opinion because i have not been able to spend some time with the 6se.

Bottom line: another vote for the REF75se.  Not the ref75.  Big difference!   I listened to MacIntosh years ago.  I found the Macintosh to be a fun listen now and then, but too bloated and exaggeratedly tubey.   I wanted some thing more natural, like the musician was in the room with me, with a hint of warmth. My cables amplify the tiny bit of warmth I hear in the ARC. 

I would also suggest if you could afford it, eventually maybe, pair it with the REF6 Pre, to me it sounds like they were made for one another.  I added the REF6 after I had had the REF75 for awhile, and that changed everything - I could no longer listen to how my system was sounding because the music kept distracting me.  Except for adding a server (Aurender) I haven't changed anything in a long time.

Spending money on Head-Fi now.