Amp recommendation for B&W 801 Matrix SII speakers

Try risk free Crown XLS4000. It's pro audio amp capable of delivering clean and detailed sound with gobs of power for 801's. To my tastes it's definitely better runner vs. McIntosh 452 and it's small fraction of the price of all above mentioned with money back from most of pro audio dealers.
There's also a discussion here about downgrading to pro-grade and remaining super-happy with performance and built quality.
Sounds crazy ($800 amp for $10k speakers), but worth trying

Try your MC275 first before you spend your money.
The PASS will work fine, as will any high current SS amp, although the PASS will probably sound better than most.
Back in the day, many liked Classe' amps with B&W, maybe because quite a few American audio shops that sold B&W also sold Classe', but you can probably do better, IMO. Here are three options;

1. If you like Class A power, you can consider something from the PASS XA series or, for an option at a much lower dollars per Class A watt price, try something like the Clayton M300s I previously owned.

2. For high power at a reasonable cost, a used McCormack DNA-500 would be a bargin. In stock form, many found it to be competitive with the best of SS and used they are going for about $3.5-4K. Steve at SMc audio (the original designer of that amp) has a few upgrades that can bring that amp to an even higher level of performance.

3. I just recently auditioned the new 400 wpc, NC1200 Ncore Class D amplifiers by Acoustic Imagery, the Atsah monoblocks. I was impressed and found them to be fully satisfying and quite musical, if just a touch below the absolute performance level of the Clayton M300s, based on a direct comparison in my system. Call Michael at TweekGeek and ask if you can audition a pair in your home with your speakers. You may find that you do not need to look any further.

I hope this helps. Options are almost endless so take your time. If it were me, I would probably start with an audition of the Atsahs and then if those do not work for you, any of the other recommendations above, including the PASS, should sound good. Also, there are for sure other good amps not mentioned in this response. Good luck.

I'm a huge Mc fan, but agree with both Czarivey and Mitch2. The MC452 was not one of their better efforts, IMO. I gather you've tried your MC275 and probably found it soft in the bottom end with the 801s. You will need to get serious about going for higher current to bring out the best the 801s can offer.

When I was auditioning stuff a few years ago, I thought the MC302 blew the 452 clean away. The 302 was far more musical and neutral in comparison. I also found it superior to a similarly powered and priced Krell (don't recall the model now). After getting the 302 home and running it with my Rogers Studio 1s (very similar to the 801 in efficiency and balance) and C2300, I was very pleased with my choice and remain so.

The only change I've made since was to go with a C50 in place of the 2300. The tube warm-up time was just too long for me and I can't leave things on 24/7 because I'm rarely home.

Good luck & happy listening!

The highs are bright/harsh on the B&W. I would look at something from Rowland. Model's 10, 12, and 112 would be a good match.

You may want ti add Classe and VTL amps to your list. I've used both with my B&W 801 S-3's. I spent 6 months listening to Classe CAM 350 and VTL 300 amps. Each amp never lacked the power to drive my 801's. Both are quality product from well respected companies.

You dont need 350 watts for B&W 801 series II speakers. The best I have ever heard them was with Mark Levinson Model 20 class A monos. If you go this route be sure to mate with Levinson preamp.

Effischer, I am really surprised that you liked the MC302 better than the 452. I thought the 302 was Mac's entry level amp and not quite up to the quality of the rest of the line of current Mac amps.

i have heard some about Rowland amps. I will check them out.

MC302 is a newer design than the 452. They changed something and it definitely improved the sound, IMO. That's the fun of the hobby - finding the pleasant surprise!

Just did a double-check on Audio Classics' site and realized I made a mistake - had auditioned a 402, not a 452. Not sure how much difference it really made; the 452 is really only an update of 402. So many variables when doing demos, anyway. Still wouldn't trade my 302 - it works wonderfully in my room with my speakers. Price does not equal quality and is never the bottom line.

BTW, I believe the 801 Series II are some of the finest speakers ever made by anyone. I'm way jealous!

I have liked all of the Mac amps I have heard. I am sure the 302 is a good one. I really like my MC275 but I think these B&W speakers are going to preform better with a solid state amp. I do appreciate all of the suggestions so far.