We are currently using the Crown macro tech 5002VZ power amps to drive the JBL Vertec. We run in to some problems with them - 1. There seem to be no sound coming out even though the display is perfectly normal! The "temporary solution" that got us through the show is a little physical abuse - (lifting the rack up an inch and dropping it). There's got to be a better solution 2. The other problem is that when we turn on the amps, everything seem to be working fine - but when there is signal coming through, the green IOC light switches on stays on (NO OUTPUT). It goes away when we turn it off and on again, but the same situation persist Has anybody come across these problems before?? PLEASE help!