My Polk 10" powered sub was emitting a very loud snapping pop noise when intensely powerful DTS or DD EX soundtracks on DVDs were turned up to a certain degree on the receiver; this notably happened on "Gladiator" when one of the chariots hit the wall (running in DTS), in "Episode II: Attack of the Clones" when the senator's ship explodes in the beginning (running in Dolby Digital EX) and even in "Daredevil" when Matt hears the I.V. bag in the hospital dropping the formula into the needle in his arm (running in DTS) -- dont even get me started on the awesomely loud depth charge sequences in "U-571" which would rattle my apartment to death, but also snap and crack my sub like crazy.

Since encountering the problem, I have physically lowered the sub's output volume on the rear of the unit (which was up pretty damn high) as well as lower the sub's caibration level in the receiver's setup. I thought this had managed the problem, as the explosion scene in Star Wars didnt crack or snap the sub any longer at, say, 55 on the receiver's volume display. But a good few weeks back, when having a friend over to watch "Episode II," I had the volume up to about 57 or so on the receiver (which is VERY loud for a DD EX or DTS soundtrack) and during the scene toward the end where the rhino-creature slams into the pole Natalie "Im A Piece Of Ass" Portman is on, the loud, startling pop happened again in the sub---proving if I wanna run these DD EX or DTS soundtracks loud, the sub STILL cant handle the bass unless I turn the sub's volume down even more.

Short of continuing to lower my sub down to almost inaudible levels (for every other device such as CD) or changing it up for a 12 or 15 inch model, what can I do to correct this? Should I bring the sub's level down even more in the calibration setup? Right now, it's on "+6" which is where the left and right mains and surrounds are set. Is this happening because my sub simply cant produce the amount of bass my receiver and listening room are demanding? I thought a 10" model would be plenty for a studio apartment.