Is the PS audio M1200 D class amp worth buying or should I stick to A/B class mono amps

Instead of asking people how something sounds which isn’t going to help you because everybody has their own preference, ps audio has a 30 day return policy. There is no better way to see how something sounds when you can use it in your system and in your room, especially with class D amps. 

At the risk of engaging in hyperbole: they are SUPERB and an incredible bargain. I’ve used them to drive everything from Avant-garde Duo Omega G2’s to Martin Logan 15A’s and CLX’s to MG 20.7’s ALL with outstanding results. Wonderful tonal balance, ENORMOUS soundscape and wholly unrestrained dynamics! Never harsh. In fact, “tube-like”. PLUS there’s a 30 day in home trial period. Can you tell I like them? 😀

And yes, I was once tube devotee exclusively. ARC, VTL, CJ,  etc. But on my CLX the PS Audio were clearly superior to CJ ART 150. Those are all great amps, but the PS Audio bested them. 
 

caution: the M700’s are NOT THE SAME. They don’t have a tube input stage. 

I first had the M700s, which are excellent VALUE, but $6600 for the M1200s, not so much. Don't get me wrong, Im sure they are excellent amps (M Fremer kept his after review), but compared to what, price-wise? Long before PS introduced the M1200s, I bought a EVS 1200 which is based on the identical ICEPower AS1200 modules, but a highly tweaked product by Ric Schultz MSRP $2700!!! I loved this amp until I got a LSA Voyager 350 GaN amp, which trounced it IN THAT SYSTEM CONFIGURATION! Since then (about 3 months ago), I did a complete cable change with Ali-Express DIY HiFi, mostly Odin 2 silver and gold, and one component change; Audiolab 6000CDT replaced a dead Marantz HD CD-1 (used as a transport). I have long wanted to replace my Solid Steel vertical rack, thinking it interfered with the back wave of my EP 3.4 open baffle speakers (click on my UN to see pics). Recently, I came across an incredible deal locally paying $170 for a DIY solid maple table with a 5 x 2 x 2" top, so was able to pick it up. While breaking down my system from the vertical rack, I placed my Voyager (top off but resting sideways on the amp) on a chair. Alas, it slipped off and the top nose dived into one of the modules. It looked fine, but when I set up the horizontal system on the maple table, and turned the power on I had major fireworks from the right module: it's dual mono.

Fortunately, I never sold my EVS 1200, which I had not listened to since installing the Voyager well over a year ago. How would it sound now? Well, I am totally blown away, and would highly recommend it, but... Ric only made ~ 16 of them-sigh! If you don't have $6000+ to spend on the M1200s, do a search for the EVS1200 (or the Voyager; several available ~ $1500), FYI, I have yet to see a EVS 1200 for sale. Until I get a replacement module for the Voyager, I won't be able to A/B them, BUT, I am very very happy with my EVS 1200. 

hth