I haven't read the entire thread - way too long. BUt I'll add this - driving with your car's window down at highway speed, from what I read in an article by an audiologist, is about as damaging as 120 db. Lot of high frequency sounds being produced by the wind rushing past the opening and/or your ears. Convertible drivers and helmet-less motorcyclists are exposed to even more of that. Since reading that about 7-8 years ago I don't roll down MY window or I use the foam roll-up earplugs I keep in the console for the ear that is facing outward. Has seemingly helped my tinnitus and overall hearing tremendously. I was driving around my uncle who has tinnitus, first request he made was for his window to be rolled up, kicked his tinnitus up terribly.
Oh, if you hate plugs you could also consider buying really good quality headphones and using a small mic pre-amp and a mic to monitor the players around you. Like if you play in a garage and the drummer is 5 feet away from you and everybody else likes to turn it to 11. Current band plays in a very small room but we have a great headphone system.....I can feel my bass notes hitting my legs but feel like I am playing in quiet resturant. Bliss