Need A Power Source

Great site! I have a '00 VW Jetta w/ a Monsoon system. I do have a new Alpine 9815 headunit w/ XM tuner I was hoping to use. Due to the existing OEM system and my research that made it seem I would have to replace the entire system, I opted to keep the Monsoon and add the XM Skify. I then purchased a Soundgate Aux w/ 2 inputs (XM and IPod). I have tapped into the switched headunit power to power the XM Skify and the Soundgate Aux box. I then learned I would need a audio booster to match the correct output level and will also need a source of power. Since I have 2 taps into the headunit power already (hoping that is ok), I am assuming I will need a new switched source to power the booster. Does anyone have a suggestion to which source to use?? Thank you in advance.

I would tag my constant power for all of those things at the ignition switch. I believe that the constant on a Jetta is red, or red black at the ig switch but you'll want to verify that with a meter because I am not all that sure of the color. As far as the switched, I would find the turn on for the factory amp and use that to trigger a relay to feed switched power to the accessories. The relay will go like this, pin 87 will have a fused wire going from it to the constant at the ig switch, 85 will be connected to the remote turn on from the head unit, 86 will be grounded, and 30 will be the new switched power to your booster, xm, and all that.

-------------
Northstart.....or start it your damn self.

Lots of the newer VW's and BMW's have a barrier strip under the driver's side dash.  You can get switched and constant right there.  You'll have to pull a few things to get to it, but it's worth it.  Test the terminals, and when you find what you want, back a screw out and grab power. 

-------------
My ex once told me I have a perfect face for radio.