This has been an interesting and well-supported :-} exchange to follow. [Darn Crazy Internet Fad…]

Devil's advocate for a moment—What kind of hazards could be created with this PA-system outage? Would its loss generate a potential hazard/panic situation or otherwise become a critical issue?

There are PA-type systems used for facility-wide verbal emergency-egress instructions, but they are supervised [characteristics of the electrical circuits to various peripheral devices are continuously monitored for readiness and centrally alarmed.]

So it is unlikely that with dissimilarly conceived and engineered portable systems—primarily intended for entertainment applications—havw no intent of contingency operation. Although this may someday be the case, {and even routine or mandatory} the portable would not seem to qualify as, or serve a parallel function to that of a fixed system installed for the purpose.