Bill, I tried the PAAS when I first bought the 4x. Korg decided to make that sound bar proprietary to the KB sounds only, and will not process any external signals plugged into the aux inputs. I use that input for the audio out of my iPad, and it's a deal breaker, if I can't hear the full mix in my monitor. So, even though the audio signals coming in are mixed in the MAIN outs, they will not be heard through the speaker bar. Pity. I LOVE the sounds anf feel of this kb. I just need that ease of setup/small footprint too often.