What subs are you auditioning? And yes most places set up the subs way too hot to emphasize the pound which is what the general public seems to expect from a sub.
The EP400 is an absolute delight for music, it is not overpowering and blends seemlessly withe M80s. I would bet it would work just as well for the M60s.
You may just need 2 subs, one for music and one for HT. The EP400 just doesn't have enough air movement to shake the house for HT but just fills in the lower end when listening to music.
