Does "smooth high" mean a fairly flat response curve across mid to high frequencies and low distortion?
Fellow tinnitus sufferer here. Sometimes it comes along with HF hearing loss. I can't hear anything above 12,000 Hz, for example, so response above that cutoff is moot for me.
Please do get your hearing checked and ask about hearing aids as well. If your tinnitus is related to hearing loss, it may help attenuate it and also make listening more enjoyable in general again by restoring some lost bandwidth. Or if you're really lucky they'll pull a bug out of your ear and the ringing will be gone!
Take a look at the Revel M16 as a starting point, or does small mean smaller than those?