I've got a bha-1 and mjolnir currently. Will be getting either a super 7 or two mono blocks for my HE-6 in the near future. Also have experienced with the b22, WA22, Litt Dot MKVI and EF-6.
The HD600 is a can that everyone should own or try at least once. I would agree except instead of the HE500 its the HE6 for me. It took me a long time and many headphones to find an upgrade to the HD600 and the closest I got was the HE6. It's not quite a direct upgrade but as close as I could get. Everything else I've tried has been better in sound but not the same signature.
Hey Rawrster, I've noticed many times we've got pretty much the same stock. I think I had mentioned it before too. He500 -> HE6 and HD800's lol.