The most important thing is to use a realistic volume when setting the EQ. We have to be at stage volume, for a couple reasons, but it’s essential.
And, it’s easy to prove to ourselves why, simply by setting the EQ at a loud, stage, volume, then turn the volume down to something your girlfriend can watch TV on an iPad over without telling us to “turn it the F* down!”. The sound will be thin once turned down. And, conversely, setting the EQ at a low volume sounds terrible once it’s turned up. It’s Fletcher-Munson in action.
So adjust EQ at volume.