andaya

I just go a 10" sub woofer installed in my ML with a amp. I started noticing "popping" weird noises coimg from the sub woofer. The weird thing is that when ever I move the Audio inputs on the amp, it makes popping sound. Is that normal?
Shouldn't it not make any noise? Not sure, but I suspect it could be the ground wire or something that's doing this.

Any help will be appriciated, thanks!
andaya