So I buy a PLX2402 from a talkbass brother. Near perfect condition. Obviously never been in a bar environment. I throw it in the rack for tonights gig, wire it up and turn it on, no problem. Plug my Sadowsky into it to make sure some sound comes out and what I get is the most unbelievable buzz from parts vibration I've even heard. This is at a conversational volume set up in my friggan' kitchen! Thus begins two hours of tapping and vibration hunting. The plastic air ducts are vibrating against the fiber ducts, both of which are vibrating against circuit boards. The circuit board that takes the ribbon cables is vibrating on all four mounting posts. Nothing is shock mounted that I can see and it would appear that no attempt was made what-so-ever at the factory to address vibration issues. Mr. QSC I would respectfully suggest that you take the entire PLX series back to the drawing board and invest in a little rubber or clearly state that these things are totally inappropriate for use in a rack mount bass amplification system. It does however, seem to sound pretty good once you put foam under the corners of the circuit boards and tape all the air duct seams.