Sennheiser, Beyerdynamic spring to mind. If there is a culture of headphone appreciation there may also be some good amps. I know of spl, and have seen things written about Cayin and Vincent. Any others worth a look?
It never displays album artwork for me, whether it is FLAC, apple lossless, wav. What secret sauce you got? The most recent eLyric & tagNplay versions have been better, quite enjoyable.
What we need is someone with Beterdynamic Tesla T1 (600 ohm), Sennheiser HD800 (300ohm) and something like Audio Technica WTH5000 (40ohm) and a sound meter to do some measuring. Oh that's me....
I have some hum also. And the thing runs hot, or nearly hot. Don't notice the hum at the start of a listening session or during it, only when I finish up and go to turn things off.