I don't quite understand why the HE-560 is on the board and the T1 isn't. The T1, while isn't the most resolving headphone, is just outstanding in the imaging department, with instruments and voices always placed and proportioned correctly. Plus being a semi-open design, it immediately 3-5dB lower noise floor in real world listening environment compare to the Hifiman design.The imaging of the HE-560 is down right poor, with instruments all over the place. Where on earth, except car audio and being on stage, I should hear the vocalist and guitarist in front but with the drummer playing right behind/next to my seat? In stock form the HE-560 is just poor. Even my Alessandro MS2 would give better more correct imaging.I have a HE-500 myself. It took the heavily angled Audeze Vegan pads + sticking 160 4mm half plastic beads to the baffle plates to bring the image forward.
1) T1 had serious production variation - measured here. Some units came with two nasty peak bright treble drivers. Some units came with one nasty peak bright treble driver which didn't match the other one.2) 880-600/250ohms is better than T1 for much less.
Balance and product variations aside, the T1 is too crazy colored a phone in a bright way for me. HE-500 > T1 IMO. In short, T1 was a brain fart. DT880-600/250 are proly the best Beyer has put out so far.
At moderate volume level, the T1 is fine. I listen at volume no louder than my wife talking next to me (have to).
Perhaps I am just lucky getting a good T1. I use EQ all the time thus treble peaks (of any headphones) does not bother me more than poor imaging.I guess I am the rare one who value imaging capability the highest.
I don't listen too loud often either (unless doing some evaluations or on special occations). Can hear my wife just fine with open cans.The DT990 did not work for me, but they may work for you. Have you checked them out? They may be a little more open though.It may also depend on your source. What are you using for amp and DAC?
I usually listen fairly quietly and I'm not a big fan of the T1 either.