Like most have stated earlier, I too feel , 750(or used 910) plus Pa600 would be a great combo.
What I have been saying all along. Having had the PA800 for more than a year now and only using them within the confines of my living room I have opted for the ( budget) purchase of the PSR-750, as I did not see much point of swapping my PA800 for the PA600. Again I would like to say that in my opinion a combination of the PA600 with the PSR750 ( or possibly the PSR 910 used or new) is a killer combination and without a doubt the best bang for the buck. It goes without saying that PA3X and Tyros 4 have more to offer but at what price..............
regards,
John