It's been my experience that fencing with the non-speaker amp folks is just a waste of time, considering the overwhelming testimonials for the use of quality speaker amps...with most headphones, not just the HE-6 or HE-5LE.
I use, or have used, speaker amps for HD-800, HD 600, AKG 702 and 712, Beyer DT660, DT880, T1 (tubes), exclusively for over a year with STELLAR results. (Read the Speaker Amp thread if you're interested.)
Please, anyone with the "you'll blow your headphone hysteria"-- get real!
You're in good company, until the 16th century the vast majority of people, including the contemporary 'specialists' believed in geocentrism. Majority opinions are like any other opinion: they mean diddly squat unless supported by evidence. I wonder how many people would be able to differentiate one way or another between a HE-6 powered by a good (powerful) headphone amp or über powerful speaker amps in a double blind auditioning session. Reminds me of the cables argument, that didn't fare too well under controlled test circumstances either.
Mind, I'm not stating that the HE-6 won't perform well with speaker amps, only that I see no evidence of why it wouldn't fare equally well with a sufficiently powerful headphone amp system. And speaking only for myself, I think that my DAC, headphone amp and headphone already take up enough real estate.
Edited by Xenophon - 11/18/13 at 2:36pm