Internet protests over Danger Mouse’s “The Grey Album” last week show that “there’s really no way to resolve the legal issues surrounding sampling. It’s a subjective thing: It makes sense for Vanilla Ice or P. Diddy to cough up some cash and a co-writing credit when they appropriate “Under Pressure” or “Every Breath You Take” more or less in bulk to build another song, for example, but does a single snare loop or sampled “Yeah!” from an ancient funk record deserve to be treated the same? Where do you draw the line?”