Hint - if you have a girlfriend, she can hear better than you as women generally speaking have better hearing and are more sensitive to pitch than men. I used to give my ex full access to my 1/3 octave EQ and let her have at it. She asked me what each of the knobs do and I told her to raise and lower each to their maximum and minimum positions and she could get a feel for what area they affected. Then, I'd let her have at it. Of course, I'd give her something that had all of the basics nailed - all speakers were in phase with respect to one another, crossover points were fine tuned to eliminate peaks / dips in the frequency response, no panel rattles or vibrations, etc. She would sit in the car for a few hours and listen to her favorite music and just tweak away. When she was done, I was typically blown away by the results and typically left the EQ settings exactly as she set them. If I looked at her results on an RTA, it was really quite amazing how smooth the response was from one octave to the next. Occasionally, I could pinpoint a problem or two that she was unable to resolve just by listening that could be simply corrected with like 1/8th turn on the respective control on the EQ and done.
This is also a great way to get your significant other involved in your hobby. When you're giving your demos, she'll be telling your buddies, "I tuned it."