I don't use the Tascam interface so I can only be generic but this may point you in the right direction. If your synth volume is to low then there is probably a gain function of some sort in the Tascam ASIO control panel. That is part of the Tascam software. The turn local on or off is in the preferences file. Some synths need local on when using external sequencing. Some don't so that is specific to your synth. Leave local on and if you hear a flanging effect then you need it off. Otherwise leave it on. I don't quite know what you mean by the synth control panel. I took a quick look at the CP33 online and I don't see a control panel. I would suggest downloading Midi Ox and use that to monitor exactly what channel is transmitting.