I was born with a moderate-severe hearing loss in both ears. Not sure if you guys know what the cochlea is, but it's basically the small organ in your ears that sits next to your brain where the magic of turning physical disturbances into nerve impulses that your brain can understand happens. The cochlea is basically like a snail shell, and all along the inside it's lined with small hairs, and the entire shell is filled with a special liquid. Basically, the three little bones in your ear will vibrate this liquid according to the outside frequency, and the hairs will pick it up and turn that into nerve impulses.
My problem is that a significant amount of these hairs aren't even there. Not sure if I was born early or if there was some sort of anomaly in the womb or what... but the result is that there are patches of frequencies that are impossible for me to hear. When I listen to a pure sine-wave frequency sweep from 20hz to 20,000hz, I can't hear anything above about 7,000khz or so, and before that, there are about 10-15 little sections that drop out completely. This is on $800 studio monitors too, so I'm fairly certain the signal I'm hearing is quite accurate.
I wear hearing aids in both ears, so that helps a bit. They boost overall volume and they also have built in compression which is sweet because when I go to live shows, the compression just kills anything above a certain dB rating. Plus I need to wear ear-molds as well as part of the hearing aid so I'm basically always wearing custom earplugs. Last time I went to Metallica, all my friends were fucking deaf when they came out and I was just fine. No ringing, no pain, nothing. My voice was fucked but that's another story. Same thing with Satriani last year. I saw him in a very intimate bar setting, his whole band was about 15 feet away from me and him and Eric Johnson played a combined total of about 4 hours of music and I was fine afterward.
Without them though I'm basically helpless. I can't understand people talking unless they are very close to me and I can see their face, and if we're in any sort of public setting I'm basically just wasting my time trying to hear them.
How does all this apply to guitar? Well, the more you lose your hearing, the quicker it is to lose it even more, so just cuz you can handle cranking your amp to 150dB and jamming with no earplugs now doesn't mean you will be able to a few years down the road. Plus there's the issue of tinnitus as well, which as previously mentioned, can drive people up the fuckin' wall. And if you do lose some of your hearing, you're gonna be missing out on all the great stuff that MESA amps can produce. Remember how I said I can't hear **** all above 7,000hZ? Yeah, forget all the lush overtones and sweet top ends that MESAs have if you lose even a bit of your hearing, you won't be able to hear them heh. Higher range frequencies are the first to go.
I guess all this rambling is supposed to mean one thing. I have severe hearing loss so I know first hand it sucks hardcore, so don't try and be a macho guy, just know from me it sucks. A lot. I wish every single day of my life I could hear like normal people. It sucks even more for me because it was totally out of my hands, I was just born like this so I've had to learn to accept it. I can't even kick myself in the *** for listening to loud music when I was younger. I'm just fucked from the get-go. So just wear ear-plugs. If your band mates call you a pussy, then just tell them to enjoy being deaf 10 years down the road.
PS - Turn down the bass. Bass is the most damaging of all because it's so high energy. Same reason you can "feel" the bass in your chest, it's also wreaking havoc inside your ears. Deadly trade-off, I know, I still enjoy cranking way up and standing right in front of my cab and feeling my nuts rattle haha.. but just be careful you don't do it too long.
Know this: If your ears ever start to feel painful and you keep playing, you are actively and permanently damaging your hearing at the point. As soon as they actually start to hurt, stop right away. Anything beyond that is irreversible damage.
Hope all this info helps someone.