Pink Floyd - Echos
I found this song excellent for setting my gains on my mid-bass and then tuning it. The entire song is about 24 minutes long. From about 1:55- about 2:55 it plays some notes that are right on the fringe of what I think the mid-bass should be handling. I got it hitting these right and i haven't had to make a change since. beyond that, the song is just awesome.