I remember a guy demoing speakers for me... I asked to make certain the sub wasn't on because the lower frequencies were so plush. then I asked him to switch on the PB16 and he had a bitch of a time making it work.
So when in doubt: RTFM.
LPF for LFE in the AVR should be 120.
Any LPF on the Sub itself needs to be set as I described above: Off, Bypass, or to Maximum.
I really think there is something simple in the sub app you are missing. I'm not an SVS user, but... their stuff usually seems to work.
You bought this new?