Obviously the settings will vary depending on what they’re being used for, but in general it’s worth doing a quick check with your ears. Basically find some quiet, high frequency notes (like brass instruments or cymbals) and then see if you can recognize that sound when it goes back and forth between speakers. You’ll be able to tell easily if one speaker sounds louder than the other because the sound will reach your ears partially through one speaker before reaching them partially through the other speaker – They’ll “feel” like they bounce a little in your head as you’re listening to them! The stronger sounding speaker should be adjusted accordingly, so it doesn’t overpower anything else going on at low frequencies.