One of my Logitech Z5500's sub is making a vibrating noise with some bass frequencies. I already checked the inside and everything looks OK. I think is comes from one or both
Hacking the Logitech Z5500 | Page 37 | diyAudio
ABS Replacement Computer Speaker Remote Control for Logitech Z-5500 Z-680 Z-5400 Z-5450 Speaker Accessories