The DGX 670 caught my interest as I am looking to upgrade, except for 2 important shortfalls. Not so good speakers, and no 1/4 audio out. Someone mentioned using powered speakers from the headphone jack and I decided to check that out on my Casio 350. From the headphone jack to my mixer on to the amp and then out a couple of old but still good EPI towers and the sound was the same as using the 1/4 audio outs on the keyboard. So I am reconsidering the 670.