After a couple of months of research, I have settled on a way to volume-control the built-in multitimbral sound engine on this keyboard while gigging. (using a Korg NanoKontrol and a USB host app on a smartphone) This of course is not controlling the LH/RH volumes; I suppose it has been established that these cannot be controlled from outside the board. What a deficiency!
The other tragic deficiency is the the acoustic bass sound, which I use on 75% of my tunes. It sounds great, but is significantly weaker in volume than the rest of the sounds on the board. For my purposes, the super-faint acoustic bass sound combined with the inability to turn down the live keyboard part is a nearly-fatal combination. I have been jumping through hoops to get them to balance in volume (setting the keyboard touch to "Firm", editing all my MIDI files so that the acoustic bass part approaches 127 in velocity all the time)... I've only had my CDP-S350 for a couple of months, but for this one reason I think about selling it at least once every three days. It's really a shame.... Other than these problems (oh and the fact that the USB host port is restricted to disk mounting), it's a fairly nice keyboard.
