I have a Roland guitar synth connected to my Korg x50. The sounds play out of my mixer fine. The sounds from my Korg x50 play and record fine, but when I try to record from my Guitar synth I get nothing. Remember I going from my Roland guitar syth MIDI out into my Korg x50 MIDI in. I'm connecting to my PC via USB from my X50. Its as if the X50 isn't sending the MIDI signal to the usb. If I have an arpeggiator it picks up some of the notes.