Amp and sub go out when volume is increased on the head unit

 I have a 2000 Jeep Wrangler and I installed a Kenwood kmr-355u Marine stereo since I leave the top down often.  I also have six and a half Holt audio marine-grade speakers on the Soundbar and talk audios up front. in the back I have an MTX 12 inch subwoofer Thunder 4500 and an autotek Street Machine SMR 1000.2 Amp.  When I first turn the head unit on I have Bass but then when I turn the head unit volume up to about 20 or so the amp pops and goes into safety mode. I was wondering what thoughts y'all had on this I have a few ideas but I don't want to express them right now for fear of confirmation bias so just give me your thoughts I'm not sure about the gauge of the power wire.  It was not installed professionally.