There are definitely negative effects at the sound levels they're using.
A class action suit might be so obviously unwinnable that they won't care, although perhaps it would be enough get some attention. If we only knew a lawyer here on the forums who could draft one up, I'm not mentioning any names.
@Knight Shift
In my experience, complaints about a bunch of little things that are personal preference oriented (for example, which songs get played or not played) are very unlikely to be addressed. There will always be broad disagreement about such stuff.
However, a short, simple, reasonably-toned letter or email about the overly high volume and unrelenting nature of the audio in the stadium (and the RAC) might work. Also, if people have connections within the media, getting the issue (again, just volume and lack of any quiet moments) out there beyond this forum would probably help as well.
Perhaps an email copied to a variety of interested parties in the RU hierarchy. Probably wouldn't hurt to mention that people are discussing a class action suit. That might pique a bit of interest.
Again, lowering the volume and giving the fans some breaks of relative quiet is an extremely reasonable ask. Adding all the other personal choice stuff just clouds the matter, even if it drives people nuts. If the volume is lowered and there are breaks, it'll be lots easier to tolerate music or sound-effects people don't like.