Long Story short. Ive been happily stuck with my Prius, 2005. Red Color. Cassette Deck. Wont get rid of said Deck. But may need a new Receiver to upgrade my speakers. I would love to replace the god awful stock nav unit above all the music stuff. Add bluetooth or aux. I wont part with the Tape Deck because I have tapes I like to enjoy on road trips. Is there anything I can do to replace the actual NAV Unit above the deck. I never use it. planning some Audio Upgrades like a sub and replacing the factory speakers. But I may need a newer unit to select music. Is it possible, it it easy, and any recommendations for it.