Al, your comments on the HE-5 were quite interesting. The HD-800 is a wonderful headphone. It's got detail, soundtage, extension, neutrality, etc. It hits all the audiophile buttons. But for me at least, it just doesn't "boogie". I find it cool, thin, and lifeless in the middle no matter how much I try to warm up to it. On the other hand, the HE-5 doesn't go particuly deep, has an average sound stage, and an unbalanced, upward tilted, presentation. But these things "boogie" like there's no tomorrow. Best presentation of guitar driven rock music I've ever heard. Same with female vocals. They scale up greatly with power. I'm driving mine with a GM70 based set amp originally intended for K-1000. You might want to think about building an amp for these. Apparently a "statement" model is in the works. My O2 fund is now on hold in anticipation.