I just put in an Alpine headunit in my FD touring with Bose acoustic thing in the back. The rear acoustic thing works, I think, but not sure if it's working properly.
When i adjust the balance and send the music to play from the rear speakers only, i get a really muffled sound with bass. When i transfer the sound to the front speakers, everything is good but I hear no bass. Did I do something wrong?

 

If you used the scosche adapter play around with the line level outputs. Make sure the deck is not faded to the front or rear and that the balance is in the center as well. Turn the little dials on the adapter until the sound is adequate...

You can fine tune with your deck's settings (i.e. bass, trebble, fade and balance) but the adapter's line level outputs should be the coarse adjustment.