this may be a dumb question, but i've heard that the audio circuit in the spectra and A/S is pretty sensitive, and rather easy to blow. so here it is: when in the remote head configuration, can you plug an additional speaker into the 15-pin rear connector while one is connected to the head? Astro W4, remote mounted.
A friend of mine on a local fire dept wants to do this in one of their trucks so tey can have an additional speaker in the rear of the cab. i told him just to get a David Clark system

thanks
-jamie