I'm using an AX500 sub, which Ian has told me performs similarly to an EP175. I'm using M3s as the mains, and the Arcam AVR100 for a receiver. I have the sub's crossover turned up all the way, since the receiver's crossover is 100 Hz. The sub's volume level is between 1/3 and 1/2.

The only movie I've noticed this problem with is the Star Wars Episode 1, and I've never felt it with music. During the podrace scene, there are a few moments of intense bass that almost feels like somebody is giving me chest compressions.

What's causing this, is there any way to prevent it (apart from watching a better movie), and is there any risk to the sub from this phenomenon?

Thanks