The stock system is amplified.

You need to build a cable to take the aftermarket head units pre-outs and adapt them to the factory amplifiers.

Angry Kitchen Appliances: Saab 9-5 Audio FAQ

 

When I pulled a radio from a scrap donor car for my '01 9-5 I had to have the donor vehicles vin#, take it to the dealer, and have them "marry" the radio to my car. They charged me half an hour's labor too..

This aftermarket build thread from a different saab forum might offer some insight, as this guy went with an aftermarket unit as well.

Aftermarket audio head unit installation - Saab 9-5

Hope this helps.

 

Thanks for all the info. Looks like I am missing the bracket that held the factory radio in. I bought the car with no radio. I looked at the links and looks like a project. I may go to my local salvage yard and see if I can get a factory setup and go to saab and have it linked up
I was trying to install a used aftermarket, looks like it isn't worth all of this for a cheap radio! I appreciate your input!

 

OK , figured it out, this is way more simple than people want you to think. So I got a saab radio harness adapter on ebay for like $5. Wired it to my radio. Didn't realize the car has an amp built in. No sound due to amp not being powered up. I didn't connect amp wires as I didn't think it had one. So connect the amp and amp remote wires, and boom! Got music all around. No fancy harnesses, no going to saab. I just have a simple FM. CD player, and I need to get the double to single radio kit to mount it all in the dash right. The one issue in how I wired it is that the steering wheel controls don't work this way. For me, I could care less, the car is 12 yrs old and I am fully capable of reaching all the way to the center of the dash. If I get lazy my radio has a remote, lol. So this big complicated wiring of the saab radio, is actually very easy. I will be into it an aftermarket radio and about $20 for the install kit and plug from ebay.

 

So how did you plug the factory amp into the aftermarket headunit?

 

The radio adapter plug that I bought had the additional 2 wires ( blue and blue w/ white stripe) for the amp. The radio also had the matching wires. So I didn't have to do anything to the original car harness plug. Just wire my plug up and it works fine. The only issue it has is the amp pops when you first turn on radio, and I saw a fix for that in one of the links attached above, I will want to do it. Otherwise it was pretty cool. The plug harness adapter cost $5.95 on ebay, thought it was $5. Anyhow, that plug wired directly to my Sony aftermarket stereo, color codes were exact to my radio. I guess they are colored universally now? It is nice and clean. There is the option to use the amp audio outputs for the speaker wires going into the car, I didn't go that way. My radio is wired with the actual speaker wires into the plug adapter. I saw one of those harnesses in a link earlier and freaked out, looks like a mess. This way it is nice and clean. Just 1 harness from radio to harness about 10 inches long. I am very happy with it. All my speakers work and sound great. I just don't have the function of the steering wheel controls. That is possible with more wiring. I think that part is what consists of so much wiring, making the harness look scary. I just want tunes. Not a job getting them, so this way it is nice and simple, about a dozen butt connectors and off you go! No tapping into other harnesses or anything, just plug and go!