Powered sub into Power Conditioner?

My sub is straight into the wall. The MOV's in conditioners or suppressor can clamp current if the sub ask for a lot of it at one time.

Since your sub doesn't usually deal with frequencies much (if) above 40hz ,I'd go for unrestricted current delivery.

A lot of people including myself even keep their power amps off their confitioning units because they sometimes restrict dynamics. I'd think a subwoofer amp would benefit from going directly into the wall as well.

Best thing to do is try it to see if there are any noticeable effects in your system.