You may wish to work on your negotiation skills. I don't understand why you quit before bringing up your feelings with the BL, or with the rest of the band. Yet, your going to a rehearsal after you quit? Don't understand that either.
FWIW, it's usually better to share your concerns, feelings, etc. with your band mates and attempt to work things out without any baggage attached, such as the prospect of you quitting, for example. That allows you and your band mates to focus on the actual issue at hand. You state the problem as you see it, and suggest your preferred solution, if you have one. Or, seek suggestions. If the proposed solution is unsatisfactory, then and only then is the time to make an ultimatum. You just say, "I can't accept that. It's not going to work for me." Your band mates will either offer a compromise, or accept your resignation and your done. It's up to you at that point how much help you want to give them either with upcoming gigs or with finding a new bass player. Ordinarily, though, just quitting without telling your band mates why means you want nothing more to do with them and you don't care what they think. Just saying.
Next time your considering joining a band, find out how the band works out problems and who is in charge. The sound guy may just know the bands sound but has less than desirable communication skills. Sounds like you taught him that he could get away with that. Setting that aside, how much of the problem might be on you? Things are rarely 100% somebody else's fault.
The "no compression" rule? Okay, that's pretty strange. But it may just be that the sound guy wants to add compression to the bass at the sound board. So at that point, when you first heard about it would have been the time to say yes, or no. At this point, though, it's probably too late to bring up these issues. Yet, that's what you say your going to do. I hope that works out for you, because I wouldn't care why you quit if you did so without first saying why.
If your bigger than the sound guy and think you can take him, I've seen, "Shut the #$%$# up and get out of my face", work pretty good. Nobody ever said that to me. But I know how to communicate with people. Good luck.