Couple of things that come to mind here Ed. First, about the existing wiring. Most large amps require Class 1 wiring. Is what's there suitable- is it in conduit or other Chapter 3 wiring method? Are the amps you are contemplating Class 1? (Remember, if it doesn't say Class 2 or Class 3 wiring by the output is MUST be assumed as Class 1.)

The second question: is this a life safety system? If so you probably aren't qualified to install it and there are all kinds of design considerations way beyond a PA system.

-Hal


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