So basically, it's got the correct tonality, but not the resolution?

You can get an LDAC adapter that can power most headphones. https://www.fiio.com/btr3

Did you try the FiiO BTR3, it's got an App for EQ, you'll be able to turn down the bass there. https://www.fiio.com/btr3

Hi, I too noticed that I tend to get tennitus quicker with IEMs than with headphones, then with headphones quicker than with speakers. I always try to listen via speakers, if I can't, headphones, if I must, IEMs. Luckily my tinnitus is temporary, if I blast music today, after going to sleep, I...