I'm in the process of upgrading my 540i's non-DSP sound system. I spliced RCA jacks into the 26 pin connector that goes into the factory amplifier (pins 23-26). But when plugged into the external amplifier (Rockford Fosgate 325.1), no sound comes out of the stereo. Is this loading down the headunit's output? Can the headunit's output drive both? When disconnected, all's well. I checked to confirm that RCA connectors are not shorted.

thanks, Scott

Just make sure those rca's are spliced into the input side of the amp. Also make sure the polarity is correct. The factory radio can still power the factory amp and t-off into the aftermarket amp too.

See my post on your other thread. You tapped a tweeter and mid-bass output - there is nothing ther for the sub to play...

d-