The accusation for more than a half-century is that rock’n’roll is the devil’s music and that such satanic influences will inevitably infect those hapless youths who cheerily gobble up all those records. But what if, “Studio 666” posits, evil forces really were channeling their malicious doings through the minds of famous musicians?

That’s the admittedly half-baked setup for this new horror comedy, which on its face