Audio Systems: amp makes noise & shuts off, rca cables, pioneer 2

Question
Hi everyone,  My system has a pioneer DEH-P5800MP head unit,Audiobahn ALUM15N sub,pioneer  2- TS-D161R 6.5"REV 2 way 260W,2-pioneer TS-D691R 6X9" REV 2 WAY Speakers and a BOSS audio GT980 amp it all sounded and worked good for 14 months. The power supply went bad in the amp,I sent it to BOSS audio for warranty repairs.I refit it and now it has a high pitch noise coming through the speakers all the time.I tried another amp a Lanzar vibe531 and the noise happens for 2 seconds and the amp shuts down.I checked all powers,grounds,connections.RCA cables but they  look ok .Does anyone know what could be causing this?And BOSS audio wants me to send the amp back to them and pay another 30 dollars shipping after they just repaired it,they refuse to offer any help over the phone!! Does anyone have any suggestions?


Answer
Since the same  thing occurs with another amp, the amp is not the problem.  There is a problem with the input to the amp.  Your head end is sending a high frequency signal to the amp.  It is possible that the head end is sending a high enough frequency that you are only hearing part of it.  This could account for the amp getting smoked.  The head unit needs to be examinesd by a tech so that the output can be seen on an oscilloscope.
Dan