Sounds stupid but its not haha.
I always listen mainly the guitar, figuring out it's rhythm to train my ear. Then a friend told he listens each song 5 times, each time paying attention to a different instrument.
I tried that and I'm learning a lot about drums, bass and vocals, I think this is a very good thing for those composers who create the entire music and percussion.
So.. do you also train your ears while you listen??
I listen to the drums and guitars mostly.