try to unhook the speakers. Turn the dial up to 150 should get something , then start to dial it back to 100, 80hz.
Also start with the volumn dial at 50%.
never mind looking at the driver, I only have the 350 and I cannot see it move but I sure hear it.
Put your fingers on it and feel the vibration. Then shove your head in a corner of the room. You have to hear something.
Another thing is you said next to your bookshelves, so I assume they both are up front stage. Check to see if they are in phase 0 or out of phase 180. Probably doessn't help if one is in phase and one is out of phase.
Also, maybe your in a nul ..... how far away are you sitting ? move your chair and put on sub there, and turn up some tight bass music something with good lick drum to start ( Niclkleback ) and do the sub woofer crawl. Mark the spot then crawl around to the next best tight bass spot. Then move the subs there. Put chair back and see if you hear a difference
