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

PS Audio's S300 is a stereo amp and their M700 is a monoblock, so yes, they use different modules.

Peachtree Audio has been producing digital amps for at least 10 years. Many variations available; many include a tube based headphone amplifier. Prices very reasonable. Great deals can be found on ebay.

The D doesn't stand for digital. Can we please stop with the digital amp thing already? That is incorrect. There is no such thing as a digital amplifier.

Class D amps are analog!

https://www.psaudio.com/pauls-posts/bashing-amps/

If it's in your budget, you might want to look at Theta Digital Prometheus Amps (sometimes used pairs come up on Audiogon).  I had them in my system for 6 years and they performed perfectly.  Class A ratings from the hi-fi mags and impressive feedback from other audiophiles when listening to my system.  The amps are in my brother's system now and are sounding awesome there.