As folks overhere know by now I have the Korg PA800 in combination with the PSR750. A great combination but as you seem to prefer the (cheaper) new PA600, count your blessings, add a PSR750 to it ( as Diki says you already have a very good harmoniser) and be happy. Perhaps it I had not already had the PA800 I would have gone for the same solution. Price wise I think nothing beats a combination Korg PA600 + Yamaha PSR750.

regards,
John