Cleansweep taps into the speaker wires to get a signal...cleans it up and then spits it out via RCAs. I've used this product before many times in the past. Great if you want to keep the factory head unit and add amps/subs/etc. If adding subs, tap into the rear most speakers so you aren't running wire all the way down the car.
350Z TT - SOLD!
2011 X3 xDrive35i