Soundproofing yr band room

So we just moved into one of those weatherboard miners cottages that are basically flush up against one another in the street. 4 doors down it wasnt so bad, there was space + the hallways in each home to lessen the noise, but now our band room's wall juts right up against the neighbours wall of (presumably) a bedroom or living room in their place, with no brick and little space. Its probably worse than when we were in an apartment.

The neighbour came over y'day when R was in mid-shoegaze noise, and politely asked to turn it down a smidge; in all honesty though, it wasnt that loud :(

We rent. Short of the expense of rockwool (and I assume it is expensive and would it even do much?) is there anything we can do? Move the amp to the other wall? Tack up foam? Kill the neighbours?

rockwool isn't massively expensive - though you probably would be spending $2-300ish getting enough to make it worthwhile, and that's not including the cost of covering it. if you're planning to stay for a while it would probably be a good idea though

other solutions involve a lot more construction ... like building a second interior wall with studs spaced in between the main wall studs.

Does rockwool really work? Would it stop the neighbs hearing the noise? (there's also a long window that obv we cant plug up with rockwool, but it has a heavy curtain)

I cant see how we'd get permission to tack anything up anyway :(