when I step on the gas, I can hear very subtle whistle from the speaker.
and... buzzing all the time.
This may not have anything to do with the amp being bad at all. It could be a grounding issue. The noise you are hearing is the sound of your alternator being amplified by your AMP, therefore, gets louder as RPM goes up. Has any electrical work been done lately??? If so, one of two things may have happened.
1. A power cable caring 12V+ is touching or near the Signal wires going from the head unit to the AMP.
2. The AMP is not Grounded Properly, or the Ground Cable going from the AMP to the Chassis is loose. If the amp is an after market, make sure the Ground wire is as large of a Gage (AWG) as you can make it, preferably 4AWG. Also, make sure that the ground wire is as short as you can make it; hopefully less than 3'.
**** There is a misconception that the Ground wire would work better if it's run from the Battery. This is absolutely untrue. The longer the cable the more noise it will pickup along the way. Use the nearest Ground. Better yet, Make your own (just don't drill the gas Tank.)****
Have you installed a grounding Kit lately? If so, it's possible that you have not tighten one of the Bolts. One more thing, depending on the area you live in, corrosion might effect the quality of your Ground connection. Remember, ALL THINGS MADE WITH COPPER WILL GET OXIDIZED WHEN COME IN CONTACT WITH AIR (yes even oxigen free wires, it just take longer.)
