Thank you for your quick response. I'll try it out when I have the Yamaha.
I wonder if I could use the phone out from the MG06X to the LI?
Sure - on the L1 Compact, there's a 1/8" stereo input you could use. But if you want to run the cable more than 20 feet, I'd probably do it the way I showed you above because this will give you a balanced connection.