-
Yes, a small rehearsal room was what I think actually triggered my tinnitus and has slightly blunted my hearing (for speech in acoustically poor settings at least). The problem is that once it's loud everything just gets perceptually compressed so you can't hear any particular instrument over anything else, which leads to everyone playing louder just to hear themselves (I've heard of the same problem in brass band practices too). The answer is just to keep it down or hand out earplugs all round. Now I have some of these, which I've even worn to the cinema and they're really good.
ffm-
Some years ago I bought a set of protective earplugs from these people: https://hearology.uk/musicians
They don't seem to have them in their shop any more, but they are excellent and designed to protect your hearing without muffling or changing the sound too much - ie specifically for musicians.
Regal
I did a thing with some pals a while back for a charity gig at the Black Heart in Camden. We had to rehearse for a few weeks beforehand so it was back to the rehearsal rooms for the first time in the best part of a decade.
ENTIRELY too loud. ENTIRELY. They give you these hundred watt stacks so of course the guitarist turns up loud, so then the bassist has to, so the drummer has to compete, and before you know it the singer is screaming into the PA at max volume and feedback.
I felt like putting a complaint into environmental health.