91 Accord, Engine noise

I sold a friend of mine a Planet Audio VX6005, a Pioneer DEHP-6800MP, a dash kit, and some fairly decent stinger twisted audio cables. The car is BONE STOCK...He does the install....acoustical tachometer...BIG TIME. You know, I told him, put the power on this side, put the Audio cables on that side. It's a simple install....for anyone. The assistance I have given so far. Reground the deck, no change. reground the amp, no change. We went from a seat belt bolt (I know ) All the paint is gone from the ground locations....all 3 points. I have also tried grounding the RCA, no change. The next thing we will try next week is to run some new audio cables across the seats to see if we can quiet things down. The only way I got things to quiet down, was to adjust the input sensativity, and adjust the gain.....no noise, but no volume. The mids are stock, the sub is a vortex DVC 10. No big 3 either....it's all stock, cept for the intake and the coffee can muffler. Let me hear some ideas guys....

And of course...THANKS !!

100:1 that it is the cd player.