Yes, it's indeed great. Even without my DAC (I'm currently visiting family) the Sonett 2 / HD 650 combo sounds natural and full bodied. Bass is tight, mids are sublime... and the biggest difference initially to my ears is a much deeper soundstage. Even more so that my Crack/Speedball. I'll have better impressions when I get home and more time to spend with it. But I think I'm completely smitten with this combo.