The Icom 756pro series uses the same dsp chips as the 545 and has none of the bleeps and bloops of the 545 dsp firmware. That being said, the 545 is infinitely more bandwidth adjustable and has a working synchro, compared to the pro series. Also, the pro series features that nifty fish finder, but be warned, once you start using a fish finder to swl with you'll never want to go back.