Hello, first post. I got some new Z-680's for christmas (I payed for half) and the sub has a really sharp rattle coming from inside... I've heard of people having this problem, but I havn't heard a definative means to correct it. Anyone with experience on these speakers (particularly the sub) please let me know what I can do. I would also like to ask if anyone has a PERFECT set of these, so I know they exist at high quality.