Yeah, easy... if you've got the necessary gear.
Do it your way, or...
DI record a guitar track.
Make judgements on the results.
You'd need either a DI box, or an interface with a Hi-Z input, to get the dry signal, and an interface with a spare output, the gadget that get's the signal down to 'amplifier input level', a mic, to get the signal out and back in to the 'puter.
Once you've got your tracks for comparison, you can (should) use your ears, though you could watch meters and spectrum analysers.
Actually, your way makes more sense, since you wouldn't need half the gear in my way