I found the below on the web somewhere a long time ago and think it's worth sharing
Amp setup for room type
Goal - Find the frequency with the best balance of power and definition, avoiding a boomy/muddy sound from being too low and lack of power from being too high.
Process - Pluck open E while adjusting the bass shelving frequency, listening for the point where the power and definition are maximized.
Goal - Find the frequency where the sound is strongest.
Process - Play 5th fret harmonic on the G string while adjusting the Lo-Mid center frequency, listening for the point where the harmonic is most powerful.
Goal - Find the frequency where the sound is the most "aggressive."
Process - Pop open G string while adjusting the Hi-Mid center frequency (starting from low) while listening for the point where it sounds as if a blanket has been lifted from the cabinet. Going too high results in an overly bright, unpleasant quality.
Goal - Find the frequency where the brightness of the sound is "most pleasant."
Process - Pop open G string or while adjusting while adjusting the treble shelving frequency, listening for the point where the brightness is captured best. The same blanket lifting analogy can be used to find this point/range. (And this can alternatively be done with the sound of rubbing the strings - I don't find that works for me)
After center/shelving frequencies are set, cut/boost to taste/room.