Clb02l

i have a 2015 Hyundai Veloster. I have decided to keep my stock radio on account of loosing climate controls display and temp display that I would loose by going with aftermarket radio. Anyway I had installed a Memphis 5 channel mclass amplifier to push my surrounds and my Memphis m6 subwoofer. I also am running a Memphis crossover to balance out the audio. System sounds fantastic other than one huge problem in my opinion. I am getting audio noise or static. Engine on or off. It's quite annoying. Installed, whom is a very nice guy says it's the radio(head unit which is factory) says it's because the signal coming out of it is so low and too compensate u need to turn the gains on amplifier up more than usual. Even with gains turned down you still hear static through speakers. To see if it was the radio and not rca"s or the running of the power wire, he took his phone and went straight to the crossover and hooked his phone into that and zero static. If it was crossover or rca or power or ground wire there would be static. Since he was using the phone as a radio(so to speak) tells me that it's the radio. Cause it goes from radio to crossover. Hook phone in before crossover and it goes away. Does anybody have a suggestion that him or don't know about of thought of. Please help cause this static is really a pain at low volumes. I don't be necessarily listen to my music at high volumes all the time. Any help here would b appreciated.