Just in case this might help someone.  Basically, should have been evident, but the 'best' way to plug in basically any amp without effects loop such as the Spider or whatever, is simply to bypass the POD Go's cab block and plug to guitar in, that way you're using the amp's cab instead of a simulated cab.  Sure, you're losing out on the cab block of the Go, but honestly, just messing a bit with the cabs and the L6 Spider, I'd recommend that.   If you want to use a Go with a Spider, I'd