Audio Systems: Does 2001 Yukon factory stereo have outputs, yukon xl, factory radios

Question
I have a 2001 Yukon XL with the factory AM/FM stereo w/single CD player in the dash.  I would like to add a powered subwoofer that I previously had in another vehicle.  I'm thinking that I will need a preamp output to get a clean signal for the sub.  Does my factory head unit have a preamp output.  If not, is there another way to get a clean signal to the sub from the factory head unit?  Thank-you.

Answer
Hi!
I don't think so, not many factory radios have line outs since they are designed to work with the included equipement, but a simple and cheap solution is to add a high to low adapter in one of the speaker channels (you can add a "y" RCA adaptor at the output) you don't need to remove the speaker from the channel that is going to be used since the high to low adapter has high impedance.