~ ~ ~ 00 Solara Aft. Market cd player Problems..

[DownDarkly]

So we got a Blaupunkt London MP37 put in a few days ago... I noticed a very high pitched "squeel kinda humm" sound come out of the speakers..we contacted the guy who put in the cd player and said it could be the factory amp thats in the car?? Has anyone had problems like this? If so...ppleease help me out.. the guy wants to charge us another 400 bucks just to fix the damn thing.. what a jew job..
P.S. the sound goes to the engine rpm's.. headache 24/7..

Any help is needed, thanks!