Rodrigo y Gabriela
on infinite repeat. That album was made for selling Grados. If you listen to that album on a good Grado and don't end up buying a Grado then something is wrong with you.
I'm going to break with the groupthink and mention some non-rock music styles that I like on my SR325is.
Jazz: like Sonny Rollins; Medeski, Martin & Wood; Chick Corea; Jaco Pastorius; etc.
Blues: traditional, electric and acoustic; Stevie Ray Vaughan, Roy Buchanan, Keb Mo
Bluegrass and bluegrass flavored music: like Jerry Douglas, Russ Barenberg, Edgar Meyer in "Skip, Hop & Wobble"; Bela Fleck in "Drive"; etc.
String quartets: yeah really, string quartets become interestingly involving
That's not meant to be an all-inclusive list. Apologies for all of the fine Grado music I left out.