My class D ARC DS450 was a honey of an amp. Full of power, with an extremely tight and controlled sound. I completely appreciate the virtues of class D, especially having owned a quality class D myself. However, now that I have all tubes, with a REF 75se, even with a huge decrease in wattage, I am more satisfied with the sound. I can hear more emotion, less grain, and the sound soothes me. It’s a win win. I have no doubt that class D is the future, but after hearing all tubes, I’m willing to live in the past, at least until class D is perfected and gives the same goosebumps as tubes.