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

Ever thought about biamping. Maybe see if pairing your existing solid state monos and a 275 for McIntosh or better from audio research since you have their preamp for the mid range and tweeters. You have a nice size room and maybe it's underpowered. Lots of windows which you know about and maybe it's fine. I am in love with your rack.

I'm using a McIntosh MC 901 and find it works out really well . I'm exploring replacing all of the smaller tubes with NOS telefunkens. Replaced a few of the small tubes with good results and I need to complete the transition. I like the independent control of the drivers and I didn't want to deal with complexities of crossover components so that's why I got the 901. 

The ARC has often been referred to as a reference level component. No doubt  it's of the highest quality. Mcintosh is also used by many reviewers and audiophiles as a reference. Both companies (and others) have historically produced the best of the best. I think you have a fun time ahead ! Judge only with your ears and your system. Which one gives you what it is you think you're missing ? Oh how I envy your days ahead. Nice cabin view between those Joseph's.

  "Just one more thing" to the Pirate . . . McIntosh,  mid-fi ? Thanks for the chuckle!

I don't like it when people make a post that doesn't really answer the question asked, and I will start by admitting no McIntosh experience. I am, however, recently back and forth between a Ref 75 and the XA-25, and I actually find the XA to have more midrange warmth than the Ref 75. I really like them both a lot - Ref 75 edges out the Pass on soundstage, and Pass seems just a bit warmer/fuller in the midrange.

At least to my ears , if you are looking for more warmth in an amplifier as you suggest - I don't think that the Ref 75 will scratch that itch over the XA-25.

I at one point I had both a Ref 75SE and Pass xa25 in my system. I concur with @chcook's statement " I actually find the XA to have more midrange warmth than the Ref 75. I really like them both a lot - Ref 75 edges out the Pass on soundstage, and Pass seems just a bit warmer/fuller in the midrange." I will add that I thought the Ref75SE had a little blacker background.

Let me add this: my system photos feature a few of an ARC amplifier - a vintage VT100 purchased from a friend last year.  It’s been hot rodded with new caps plus kt 120’s and sounds very good in my set up - better than I had expected!  But it has two issues: a fan which I dislike ( audible) and it’s a PIA to bias (never mind the cost of replacing 16 tubes …).  Hence my thinking a more modern, easier to deal with tubed unit might do the trick.

Anything preowned would of necessity be bought without an audition in my set up and thus it’s a bit of a guessing game.

Other suggestions welcome and thank you!