So am in the process of burning in the HE 6 on a Meier Classic, waiting for my Robinnette box to arrive so I can try it with couple of speaker amps I have. It sounds ok on the Meier, pretty listenable, highs are smooth, bass has reasonable presence (quite neutral bass), but doesn't sound like a TOTL HP.
Plugged it into WA22 just for kicks, Wow. Didn't expect this ! Bass has a solid 3D thump, Soundstage increased, highs are more air, extension. NOW it sounds like a TOTL HP. I am using an Audio GD NFB 7 dac (balanced) with WE 422A +TS 5998 + TS 6SN7 & the general consensus is a good Speaker amp will further improve sound. Hehehe... Can't wait.
Forgot to add...I listen to 70% EDM & 30% Rock (some pop/vocal). I started listening to HE 6 + WA22 with some EDM , then at 11.45 pm I made the mistake of switching to Rock / Vocal music just to test couple of tracks & the plan was to retire to bed by 12. I queued in "On Every Street" , I had goose bumps after 2 mins, Mark Knopfler's voice never sounded like this before. So started queueing in all my fav vocalists - Nora Jones, Dido, Annie Lenox, Otis Redding, Don Henely , Texas etc. This is the best HP I have heard for vocals, so natural, intimate.... I went to bed with bloodshot eyes at 1.30 pm but with a happy grin on my face.
THIS GUY GETS IT!
So many have tried to convince themselves a headphone amp was sufficient, but have failed to reach enlightenment.