2001 Stereo Problems

Just got a 2001 Tahoe, and I noticed some problems with the stereo. It has pretty bad reception and the Speed-Compensated Volume (SCV) feature also doesn't work. It just has the basic Delco single cd stereo, however there was a 10-disc sony added. Is reception a common problem with this model or is it likely to be affected by something else?
The car also has an remote starter. So I am not sure if adding one of those things might have screwed up the wiring.
Any suggestions on what to check ?
Any help would be greatly appreciated....
Thank You !

If your rca's for the cd changer are next to the antenna, this may cause some distortion due to the amount of power generated from the rca's

What is in it now the delco or the sony. Do you have onstar? even if it's not in use. Is the bad reception on the radio or cd play?