Which Class D Amplifier? PS Audio, Ghent, Nord, Merrill or other???

tweak and others, just a curiosity question. In my rack space is at a premium, so placing amps on separate shelves would be a problem. Is there a relatively inexpensive sheet of some isolation material, that would not impact the finish on the lower mono, that would prevent whatever it is that causes the amps to sound better not stacked? So they can be stacked without negative sonic impact? Is it possible the sonic issue when the monos were stacked was just a sonic fluke of the stereophile reviewer’s listening room, I have not read anyone else experiencing the same?

no sonic fluke, interactions between the 2 modules 

can you get a long board that extends beyond the rack so you can set them side by side?

Steve, always good to hear positive feedback from an actual owner

Tweak1: get those anti-vibration blocks that were cited in the Stereophile review. I got a box of 48 of them for about $26 and they are great!!! I put three of them under all of my components.

https://www.supplyhouse.com/DiversiTech-MP-2E-EVA-Anti-Vibration-Pad-2-x-2-x-7-8

jetter,

     The Stereophile reviewer heard significant sound quality improvements with separating the PS 700M monos and having them both on amp isolation stands rather than stacked.  
     I'd suggest just trying the amps both ways in your system and determine if you perceive the same significant improvements he mentions.
     If you do perceive large improvements, buy a couple good amp stands and locate the amps separated by placing one on each side of your rack on the floor or place one beside/behind each of your main speakers.  This would require longer inter-connects and shorter speaker wires but this shouldn't cause any issues with that.
     If you don't perceive large improvements, buy some sorbane pads or the blocks cited in the Stereophile review and stack 'em.
     I use thick maple amp stands (from Mapleshade) with conical brass spiked footers on my class D monos but I have room on the 6' wide top shelf of my rack with one at each end for a symmetrical look.  This works well but I never even thought of stacking them ( they're only about 7"w x5"h x 12"d) so I never compared stacked to separated.  
Tim