86 Preminum sound

Anyone know if there is a way to bypass the preminum sound amplifier on my 86 mustang, I can't seem to find one anywhere.

From what I gather they did away with the switch in '85. The diagram I have shows the switch was installed from the black/white wire #287 coming out of the head unit which looks like it splices to the speaker grounds. From that splice it goes to the switch. From the switch it comes out as a White/purple wire #829 into the Amp. The later wiring I can see only the #287 wire going directly from Head unit to Amp.