Running 5.1.2 . Klipsch all around (rf3's and rc3 rs3.. Klipsch ceiling heights) Denon 3500x. My sub sounds good most of the time. Music bass sounds tight and clean. For movies most of the time bass is good. But at times(hacksaw ridge gunship shooting scene for example). I get some rattling when I feel it should be more bass. I did a quick look and everything appears tight. I haven't torn it apart yet and looked deeper inside. The sub is older but should be capable. It's a dual 12 in ported sub. I have tried all the different tuning with it with same effect s. I don't recall it ever doing this before getting the new Denon receiver and using audyssey. Audyssey has the sub down pretty low. On the gain dial it not even on 2 out of 10.. and in the setting at like -9. Is it possible maybe the gain is just two low? Or maybe the drivers are just tired...but most of the time they sound fine.. any thought be great before I buy new drivers or sub..