There's nothing wrong with surge suppressors, but "conditioners" often have a transformer of their own, which when placed before a high-draw device like a sub or amp, will limit current and hurt performance. Only if the conditioner states that it is not current limiting, should it be used before anything with a large amplifier.
Of course some esoteric, several thousand dollar power distributors (like the Weizhi Precision PRS-6), do nothing, so they're safe to use. Not that anyone should buy one in the first place.
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs