05 cavalier stereo problems

Hello, I was wondering if anyone knew off hand if the stereo system for an 05 Cavalier Sport was an amplified system? I would think it would have to be to get any power to the speakers, but I am having problems with a Metra GMOS-04 harness adapter I bought to keep my On-Star intact and it seems to be cutting out like I am over loading it when the volume gets too high with my after-market stereo. It also cuts out when I switch to On-Star. It does do what it's supposed to do with these exceptions. I emailed Metra and the guy asked if it was a factory amplified system and what amplifier was it. Since factory amplified seems like it means what comes stock, thats what I said. It's not a Bose or Monsoon system, I know those systems would have separate external amps or amps on the speakers. I'm guessing it's the radio that is the amp. He said to call the dealer and see and if it was an amplified system and to email back and if not to switch it with a GMOS-01. I looked it up and the packaging is exactly the same, words and everything, as the -04. This is taking me all week to figure out and I'm thinking by now I should have just returned the thing and spliced into the harness again. I am selling the car and would like to keep things stock but for some reason the stock radio lost the right side speakers, and its not the harness cause all channels work with this thing. so I am trying to hook my other head unit back up and want the on-star to work. Any help would be awesome. Thanks.    

What he meant by amplified was if the system had an external factory amplifier. You can test if it does by trying to "pop" the speakers with a battery at the radio harness. If you do not understand, read the sticky "how to figure out stereo wiring". If you can pop the speakers from the radio harness, there's no external amp.My ex once told me I have a perfect face for radio.