Stuart, As far as I know Mic to Main and guitar to Sub is not possible. You can only assign all the inputs to the same output: MAIN, SUB or MAIN+SUB. You'll need a mixer to do that. Reference: "RC50WS04: Audio Inputs and Outputs (PDF)" http://www.rolandus.com/uploads/CMS/Downloads/1938/RC50WS04.pdf Sjaak --- Scarlet One, ADSL 6 Mbps + Telefonie, vanaf EUR 29,95... http://www.scarlet.be/