Apologies in advance if this seems like a stupid question...   I'm using a PX-5S. Output is stereo via two amps. I want to now add a microphone to this mix.   Can I connect the (mono) output socket of a Boss VE-20 Vocal Processor to the (mono) Line/In input and thereby mix the output of the VE-20 with the output of the PX-5S? I Think I can (but i'm not sure). I reckon the output from, say, a VE-20 should be, in "power" terms, no different than that of any other line/in instrument (say, an electr