^ Great advice. I will second turning down the volume and gain, and wearing earplugs. If you turn down, your drummer will have to bring it down too in order to hear anything. Really ride everybody's ass and make them stay at a manageable volume. As for earplugs, these are the best cheap option:
Etymotic Research | ETY
If you get the foam earplugs, all they're going to do is block out treble and midrange and make everything muffled. The Etymotics attenuate overall volume, so everything still sounds relatively clear. I suggest you buy them for your entire band so that they don't have a reason to not wear them (and so you can get the bulk discount). This is what I do when I join a band that doesn't believe in earplugs. Initially, some are skeptical or even insulted, but I've seen people turn around completely and even thank me after they realize that I saved their cochlea.
Point your drummer toward brushes (probably not cool enough for metal, if that's what you're doing) or these:
Low volume drum sticks - Ultra Tones from Lidwish Soulutions for quiet accurate drumming
Quiet playing ultimately comes from technique though, so tell your drummer to get better.
