1998 740 electrical problem

I have a crackling noise in the rear tweeters and no sound coming from the woofers, the horn does not work and the drivers seat would arbitrarily change positions while driving or even while stopped! Now I looked at a lot of the postings and decided to do a few things to try fixing this problem. Bought a new amp from ebay, well I should say a used amp, did not fix the problem! Did change the ignition switch! Nothing! Cleaned the drivers side connection on the side of the seat and it seems like the seat no longer changes the preset inputs, so it appears like the seat problem is fixed! But it still leaves me with the horn and the woofers problem! Running out of ideas, any suggestions?