I had a bit of experience using a highly reputable and well respected class d monoblocks spec’d as follows:
338 Watt @ 8 Ohm, 676 W @ 4 ohm, 1352 W @ 2 Ohm; Gain: +26 dB; Input impedance: 47 kOhm.
I demoed them with a pair of Innersound esl’s and they sounded good but as i recall they had a sound that exhibited some digital artifacts, namely an etched outline to the upper frequencies and low frequency reproduction that did not optimize on the Innersounds’ transmission line woofers.
What made me want to demo the amps was their cool operating temperature, apparent low impedance power handling, their compactness, the reputation of their engineering staff, and the many positive reviews. The Innersounds however represent a difficult load at the esl panels and one of the monoblocka shut down at less than about 85-88db sound levels. The unit never turned back on. Sent the units back and got another pair, and the same thing happened but don’t recall if one or both units gave in.
Went back to a pair of Wolcott monoblocks (16 6CA7 tubes in total, 8 per side) and they managed quite well.
Now using a pair Sound Labs with Thresholds and they’ve been a great match with consistent results in performance from classical, to jazz, blues, vocals, movie soundtracks, etc.
Hope this helps.