Bingenito's comment re: class D amps delivering the sonic goods is precisely my experience with M3's. Yes, they sound amazing with 50 watts class A tubes but when I hooked up the 300 watt Bel Canto eRef 600's I was astonished at the sound quality. Detail, resolution, transparency and tonal density to burn. But the bass, quantity, quality, texture, presence just stands out! So I went from 100 lb. monoblocks to 15 lb. monoblocks with almost no discernible loss in sound quality. If we lose our audiophile credentials so be it. We have the music to sooth us... BTW, I'm still using tubes but I write for those considering class D - don't let circuit topology determine your options....