audio hiss / bose audio / 2011 mazda 3 touring


11' Mazda 3i Touring
using the pac adaptor for a long time i have been pulling the pre-outs for my sub and it has been working great.
today i decided to replace the cheap bose speakers for some nice aftermarket ones, and a nice 4 channel amplifier. now i have a constant hiss starting a volume 1 and is constant as long as the radio is on. it doesnt get louder as the volume rises and does go away when the volume is 0.
it is not alternating noise, and doesnt appear to be a grounding issue.
any help is much appreciated. thank you guys in advance.