I'm not familiar with the Go (last Line 6 product I used was the original GuitarPort) but do those amp models include cab sims? If they do, you're running a cab model into a real cab and that will ruin the sound. Unless there's a way to turn the cabinet simulation off, you need to run into a power amp (which your effects return is) into a full range PA speaker, not a guitar cabinet.
Kanped
joined 1 year ago
Easiest one I can think of to get you started is Virus by Iron Maiden. Just follows the vocal melody, very simple.
After that I think some early Metallica ones are pretty easy, never learned any of those myself.