but i've never had any issues with it until it fried my speakers with "dc" current" and there was no warning
Servicing the amp wouldn't have helped protect your speakers from the DC that blew them ... all the Phase Linear 400 .. D500 and 700 series amps are direct coupled with no coupling capacitors at the output to block the DC from reaching your speakers
One of your upstream components leaked some DC out of their outputs and the amp simply accepted it .. amplified it .. and sent it to the speakers which couldn't handle the DC
All these amps also have 8A fused speaker outputs in the event of an internal short
Wasn't the amps fault .. it was only functioning as designed .. it was something upstream