There is enough experience and brainpower here to know what the problem is. I just got a new passive subwoofer, VMPS 215. Not getting enough output from it. Actually, Im getting next to no output. Same results with either balanced or unbalanced interconnect between the pre/pro and the amp. Pre/pro Parasound C2 - subwoofer enabled - crossover set at default 80hz (also tried 50, 60, 70, 90hz) Amp Parasound 5-channel A52 driving mains, center, and surrounds. Amp Parasound 2-channel A23, bridged mono w/400w (8ohms), driving the sub Sub 8ohms, w/built in 50hz passive crossover CD Denon 3910 For the last 24hrs the folks at VMPS put the sub thru a break in routine, so we know it worked at that time. Im presuming either a pre/pro soft switch isnt set properly, or I have a functional problem with the pre/pro, or somewhere in the interconnect cabling, or... Been swapping cables around for the last couple of hours. Also tried running the sub off one of channels of the A52 5-channel amp. Neither one made any difference. I tried the music channels on satellite, CD via PCM (digtal) and direct (analog). Didnt make any difference. Any and all ideas of what it could possibly be would be very much welcomed.