If I understand what you're asking...the HD 800 (original) is considered bright by some. And the Beyerdynamic T1 (original) can produce hard, almost shrill byproducts when driven hard (say above 83dBA - pink noise calibrated - with my pair and ears). Although I prefer my LCD2.1 and 3F for general listening, I appreciate the HD 800 for some material. There it can leave the 3F and 2.1 in the dust. As for the T1, I had given up on it...
I haven't listened much to the HD 800 since getting Yggdrasil but Yggy's ability to replace shrill/tinny/screeching high notes with hearing-into-the-inner-detail plays superbly to the 800's strengths IMHO.
As for the T1...it sounds like a completely different hp. Yggy's bass speed and detail shows out really well - I know that's not what you're asking - and the high-notes shrillness is pretty much gone.
These observations are in comparison to several DS dacs on hand (e.g. BMC PureDAC, original Eastern Electric MiniMax). Yggy is the only MB type DAC I've heard, hence all this is FWIW, TME, BBQ etc
Great info, appreciated.