Car Stereos: Hissing noise?, ground loop isolator, conventional speakers

Question
I own a 97 Pontiac Trans Am. I have an aftermarket Pioneer deck. The car originally had the monsoon sound system with 10 speakers. I have replaced the factory front mid-range speakers and tweeters with CDT audio components, and have replaced the sail panels subs with Bazooka 6.5' subs. The only thing factory that I am using is the factory amp and the factory rear hatch speakers. My problem is that whether I am on the ipod, a cd, or the radio, there is a background hissing noise. I have checked my wiring, have tried unplugging the ipod adapter, and have connected a ground loop isolator to my deck and the hissing persists. It is much more noticeable on analog recorded songs but it still noticeable on digital songs too. Your help would be appreciated.

Answer
Hi Caleb.

There are a few things ya need to check.

First reinstall the factory radio and check for noise, if the noise persists, get an ohm metter and check the old speakers, some of those systems work on 2ohm so if you bought conventional speakers for a 2ohm system you have found your problem, did you use the recommended harness for the installation of the new deck?.

Hope this helps,

Regards.

Ed.