I tried to EQ out of curiosity. I'm using the Graphic Equalizer of Foobar. Crazy how going at -12 db at 6,3k and 12k5 is such a relief to my ears, 6,3k being the most dramatic change.
Gotta say it's much more enjoyable this way, although the treble sounds somewhat bloated and off due to the EQ. Voices are also a bit meh. Interesting how I immediately feel there's something wrong in my ears when I up these two frequencies, and it start to hurt progessively after a short moment.
I also have to admit it's hard to go back at first to the HD-650 due to the lack of details. The T1 sounds so transparent/with more resolution in this regard (which was expected though). Bass also ended up sounding better with the Gustard H10 and T1, more compact and controlled, and less "in your face". Trebles and voices remain however a huge issue :'( Even at -12 db on two frequencies - ouch to the balance - it still feel like a small (granted a lot less than before) physical relief to put back my HD-650 back on after only 20 minutes or so with the T1.
Be careful with doing quick A-B comparisons with very different sounding headphones like these. What seems to happen is that they both start to sound bad.