I have to echo abomwell's thoughts in the sense that Class D can sound fantastic on SA speaks. I use mostly tubes but I have also used Bel Canto eRef 600's (300 Watts @ 8ohms, 600 @ 4 - Class D Hypex NCore) and they produce an absolutely rich, precise, and bold sound. Actually, it might seem somewhat inconsistent (musically) to produce rich and detailed, but the BC's do exactly that. I agree with Clayton (and Steven Stone and Herb Reichart who both wrote glowingly of the 600's) that it's high time to abandon bias re: circuit topology. Let listening be the test. But, it seems to be true, IMO, that the Spatials like power regardless of their sensitivity.