A couple of questions to help narrow things down:

1) What receiver do you have? Does it have an adjustable crossover? How do you have the sub hooked to the receiver?

2) Doesn't sound good how? Weak? "Farty?" Distorted? Boxy? Hollow, like it's in a dead spot?

NO question the SVS should stomp the KLH into little splinters.

LJ

"That's some catch, that Catch-22." "It's the best there is." M22ti VP150 EP350 QS8 M3Ti