and that is an issue that is EASY to figure out with a guitar rig.
Have you ever noticed how i you walk even a couple steps out of the direct path of a guitar cabinet all the midrange clarity disappears? Or how the audience right in front of the guitar cab is sticking their fingers in their ears because it's so loud but that the guitarist can barely hear it as the sound flies past his knees?
+1
Have somebody setup a typical Marshall (or any 412 or 410) guitar stack, crank it up and play it. Then go out front and listen starting far off to one side and walk over to the other far side. Be ready to plug your ears when you get on center with that thing, but you'll notice, you don't have to get very far off center before it stops peeling your face off and starts turning to mud again.