These are rock-ish musicians who go around giving a lot of concerts (described in detail) that either pacify or rouse up the audience. They also engage in street fighting, and are part of a group that has staged a coup? I can't remember the author or any of the titles, I'm afraid.
That's the "Rock and Roll Reich" aka "Bold as Love" series by Gwyneth Jones. The first book is Bold as Love, and there are six books so far (the sixth one being self-published).
To quote Wikipedia:
Ax Preston, a mixed-race guitarist from Taunton, having survived a government-organised massacre of the official Green Party (under cover of a pop-culture reception à la "Cool Britannia" in Hyde Park), emerges from the ensuing chaos as the true leader England desperately needs. He and his friends, also Indie musicians, tackle an outrageous series of disasters, including a minor war with Islamic Separatists in Yorkshire, and a hippie President who turns out to be a murdering paedophile.