I have mentioned previously that I have just moved into a new auditeria (cafeteria/auditorium). My school spent a significant amount of their budget on our technology package... which included a very good sound system. People have been very happy with our sound (of course... they should be because our sound now as compared to our old gymnasium is like comparing a balogna sandwich to prime rib). I have noticed a couple of issues, though. 1. At our "Orwell Idol" a fundraising show akin to the Television Show "American Idol", we stumbled into a horrible feedback. No matter what my kids tried (pull the line level back, pull the master levels back, pull the monitor levels back, turn the gain completely off, mute the channel, unplug the mic line from the board) the feedback kept screaching. Finally, in an act of desperation they **inserted thought... our system has a sequential power up** turned the system off. Finally it stopped. I contacted the company who did our sound set up and they are at a loss. The only thing that they think could have happened is that our digital compressor/affects/etc etc had a glitch. Anybody here have any ideas? 2. When they ran the 750,000 - 1,000,000 feet of cable in our building, they put it all into "trays" suspended from the ceiling. Unfortunately this means that our line cables are stacked in clusters with electric runs, technology runs, internet runs, ...etc. We get a very good hum every now and then. Sometimes we even have a channel pick up a signal even though we haven't a device running through it. Anything we can do (short of rewiring our miles of wiring) to stop this? So far we have been lucky and it only hits non-essential channels during our productions (ex... our SL hanging mic versus our keyboard during a choir concert). Thanks! Tenor.