I also have tinnitus for many years but it was not really noticeable unless I'm in a really quiet room and I look out for it.
Late Jan 05, I got myself a pair of KSC-75, my introduction to the world of head-fi. For the next two weeks, I was using them almost nonstop, they were so fun and engaging.
I then noticed a high pitched sound in both ears even if I'm in a noisy environment, and in a quiet room, it can get really loud.
Since then, I've gotten myself a pair of Panasonic in-ears, the RP-HJE-50 to use outdoors. I'd normally listen at a normal volume using the KSC-75, and using the in-ears, I've lowered the vol even further until I can can just bearly hear the details. I've also cut down on my use of the KSC-75 significantly.
I've just reached my office and removed my Panasonic in-ears about 15mins ago. I still get the loud ringing in my ears even as I'm typing this reply, although the vol seems to have gone down a bit. It's like having a pair a crickets living in my ears.
I think I'll look for an ENT the next few days and have a checkup.