Spotify Mac Remote
I’ve pretty much switched to Spotify 100% for my music listening. I rarely, if ever, launch iTunes anymore. It was frustrating that the infrared remote that came with my iMac would only control iTunes.
I tested it and it works wonderfully. One caveat however is that if music is not playing from Spotify and you click the play/pause button on the remote, it launches iTunes and music plays from Spotify as well.