Changing from Radio Sound to Aquatic

[jachd17]

2004 FLHTCI with factory Radio Sound head unit AND optional HD Enhanced Sound System. (100W under T.P. mounted amp and rear speakers/pods)
   Question is when installing Aquatic head unit I want to eliminate the factory head unit/amp but still have sound from the four speakers. Since the enhanced sound system is the rear speakers/amp combination and was installed by dealer when new I have no way of knowing how the rear speakers are wired. Will plugging the factory harness into the Aquatic result in sound only from the front speakers? Will I have to run separate wiring from the head unit to the rear speakers as the bike originally came with only front speakers?

I am trying to get an idea what I am in for.

[hdbikedoc]

rear amp and speaker wires run up to the stock radio so I think you can work it in to new unit

[jachd17]

Thank you Doc. I hope the amp isn't what was causing the sound to break up something fierce when traveling down the road. Be nice to keep it.