I just got my Pc-Ultra today and I had it delivered to my parent's house since I was going to be at work. I went home during my lunch hour and didn't have much time so I just took the RCA's that were hooked into their sub and put them into the inputs of the Ultra. First off... yeah... shook the heck out of the place. Awesome! Love it! Felt like calling in sick for the rest of the day. Now nothing's been calibrated or anything...I just wanted to get a feel for it's brute strength. I put in Monster's Inc and went to the scene where the de-conatminate the entire square block. I didn't have the volume up too high really...i mean it actually was at a decent listening level...nothing out of the ordinary actually. However I could have sworn i heard a very slight TAP of the driver against the plate. I replayed the scene and i heard it again. It wasn't a "Loud clap" like i've heard people describe before when a sub bottoms out but i think it may have happened. So here's where my questions are... did i do damage already...is there a way for me to check? When i take the time to calibrate my system and I'm watching this movie at reference level will this happen again? Will using the sub cables I ordered improve quality? I listened to the other scenes of the movie with plenty of bass and it was spectacular...just awesome! I could not be happier...I just wanna make sure I'm not overdoing it already.