Inertia, I would think that combining your familiarity with the music industry with
SEO would work well, especially if you are familiar with the keyphrases typically used to search for a particular type of music business. I know from experience with my husband's site at
Home: SD Pickups, Custom-Made Hand-Wound Pickups by Dave Stephens, Stephens Design that, for example, "sound clips" is an important keyphrase that I never would have guessed if I hadn't seen it popping up in his stats. Also, without either of us doing any active link-building, he has accumulated some 1800 inbound links, with many of them coming from discussions of his product on guitar forums. Again, without this direct experience, I wouldn't have guessed the importance of the guitar forums. You probably have similar knowledge and experience that could prove invaluable to music industry clients, just as my experience working on real estate sites makes me especially helpful to Realtors.
By the way, I should mention that I've never actually spent much time, if any, optimizing my husband's site. Since he frequently adds content, it seems to thrive regardless of my neglect.