Ah, that's a point. Forgot about the 5% of copyright material rule. HOWEVER, I believe in music isn't the track as well as the entire recording under copyright? i.e., you could only take 5% of a track?
There is no such thing as a "5%" rule in American law. Fair use is judged on a combination of subjective factors, all of which we should meet easily here.
The most important is that the quoting should be done 'for evalution purposes', that is, to give the reader or listener the chance to evaluate the work as a whole by.
Regarding popular music, a few years ago I looked around on the Internet and found remarkably many parts of 26-30 seconds length, so I assume that 30 seconds has been taken as the maximum length of 'fair use' for this kind of material.
Andre Engels