Trying to put the blame on a particular synth for your tinnitus is rather silly. Any loud sound can cause this, not only synths. Ask any drummer, or guitarist. Even singers can cause themselves hearing damage, just ask Brian Johnson of AC/DC.
I've been playing drums for decades, but always with hearing protection because I know how sneaky hearing loss, and hearing problems, in general, can be. You don't notice it, and gradually you raise the audio level in your headphones a little more each day, until it's too late.
Best advice I can give you would be to go see an ENT specialist as soon as possible to identify the problem before it gets worse.
In the meantime, I would suggest avoiding loud sounds, and lowering the audio level in headphones.
I agree with you in general. I suppose I want to rule out all potential factors. Like you, I've been playing in loud environments for years (guitarist / singer in a rock band), mostly with ear protection, and seemed to have avoided any lasting issues to date.
I did think I was playing synths at very reasonable volumes. But I think a combo of playing regularly, with high-range headphones, and getting used to the Rev-2's filters has exposed me to potentially damaging sounds. I don't think there is a problem with the Rev-2 in itself, but in comparison to my other synths, it's definitely much brighter and seems to have a higher frequency range with the filter open, than say, the Sub37.
What I'm saying is I've been doing something wrong. I thinker's just that the Rev-2 ultimately caused me to notice it because of its dynamics (8 voices, two sounds at once in split mode, 8 simultaneous voices in stacked mode, playing into headphones for long, regular periods).
I think its not something to be ignored. I think the human body (ears in this case) have a way of telling us when enough is too much, and we should not ignore what our body is telling us. It sounds like your ears are telling you to scale back, either on volume or frequency. The overall "listen to your body" spiel comes from somewhat of a fitness nut (who has learned this lesson the hardware on other body areas), and has learned to live by the rule "everything in moderation, including moderation itself".
I grew up in a family of professional musicians with ear-damaging sources all around me, including being woken up so my (singer) mom could drive to pick up my dad at the club he had been gigging (lead guitarist, never a keyboard guy), and sitting in the club until he got off work.. This was in the 70's but I can remember sitting not all that far from the stage near closing time, maybe at age 4, at 1am thinking if my mom knew what the noise was doing to my hearing (not to mention the second hand smoke giving me ear infections), she would be shedding a tear. Great mom but people didn't get it then.. I don't want to paint a bad pic of my parents (they were awesome, they were just both entertainers and this was how things were in that day).
I realized my hearing sucked when I was maybe 12. It wasn't until I was old enough to escape the smoky household and go to college that the chronic ear infections really subsided. I was already about 2 years into synthesis and way longer than that into inordinately loud music.
In other words, I couldn't hear like a 15 year old when I was 15. Oddly, and despite many decades of loud music -- not only from synthesizers but because I enjoy running/working out and listening to all sorts of loud music with earbuds when I do.... I can say in my early 50s I can hear about the same as I did when I was 12. Maybe a little better, because I really learned to take care of my health as I got older and on my own, which I think has resulted in a number of health improvements.
This thread freaked me out a little, because I use headphones all the time when I'm in the home studio... my girlfriend lives with me and I don't want to hear her complain, so I only use the monitors when really refining a mix. I downloaded an iPhone app to measure the dbs coming through my headphones. Looks like in the 70-75db range.
Maybe that's damaging "long term", but jeez, what is the definition of long-term? Or, has old age just forced me to believe that volume as being loud as hell when its really quiet to others?
Back to the Rev2 for a moment -- I think it does tend to have a big dynamic range for some reason, some of the patches (both factory and aftermarket) sometimes seem to clip at times they shouldn't... or maybe they should and it's just the matter of adjustments I need to do and not enough care to each patch by the designer?
I dunno. But I would say listen to your body, above all. It matters way more than Internet advice (if you can pardon the irony).