I also have M60s and mostly use them for music. Trust me; a nicely calibrated sub would definitely enhance your music listening experience. I bought a relatively cheap sub, the HSU2.3, and for the price I love it. Granted, I've never listened to a decent sub like the EP500/600, I would love to, and see what I'm missing...

The sailor does not pray for wind, he learns to sail. --Lindborg