2004 GP GT2 With Monsoon audio.

I have a Pioneer HU with the GMOS-04 interface. I cannot turn the gain up enough to eliminate all the distortion at high volumes. I know Monsoon isnt exactly the best speaker on the market, but with the stock HU I never have high volume distortion issues.

I know the GMOS produces the "chimes". If I can live with out them, can I wire the HU in directly? Not having a switched AC source is not an issue, I can pop the faceplate off and the only power draw is to keep the clock memory.