Yeah, I really like my Beyers on both the Earmax & Bottlehead Crack. It sings really well on OTL,amps. I got to hear it on a Zana at a meet & knew then I had to get myself an OTL amp myself. It has a different flavor than the Senns, but it is such a good headphone when it is properly amped.
I've rolled several combos of tubes in & out of my Earmax in the last 3 days now & even rolled in asset of GE tubes & they sounded good. Not positive these are not rebranded tubes because of faded markings but what ever they are, they sounded pretty good. I have sorta settled on a Mullard in the middle with two Silvania's on the outside? That combo still sounds great with my 650, but ups the synergy level with the HD800 more than anything else so far. I'm still using the EE Minimax dac with it right now & will likely find it tough to go back to the iSteamer when I set it up in the bedroom, but guess I'll adjust. The HRT iStreamer really is a nice sounding dac for the price & a perfect match for any idevice, but it is still a big step down from the Minimax.
Are the Sylvania ECC86 labeled "West German"? If so I think they are Seimens... let others correct me though.