I agree with the AJ's measurement mic/pre-amp (or SPL meter) recommendation. Along with some test tones, that would be the first thing to start with. If you think you have a problem with the room acoustics, check the FR at your listening position. That will give you some indication (but not the complete story) of what's going on in your room. Then, you can experiment with speaker placement and/or your listening position.
I have Dr. Toole's book and it has been quite educational. It would be a good investment. By the way, he is
not against room treatments. He just doesn't believe in overtreating a room.
So called "room treatments" are solely for poorly designed and/or positioned loudspeakers. It's a double edged sword. They may improve one area, but at the cost of making another worse - such as killing spaciousness and realism with the HF absorption.
If you put the absolute best performing speakers in a room with poor acoustics, optimally positioned or not, they won't be able to compensate for those room acoustics and performance will suffer accordingly. Sure, treatments can possibly worsen performance in some areas of the room, but if you want to improve the SQ in a particular spot within the room, there is absolutely nothing wrong with using room treatments. Just don't purchase and place them without analyzing your problem first.
As for music to listen to for getting a sense of what's going on in your room, I wouldn't use most rock music as the standard to go by. I find that most of it is too poorly recorded to use as a reference. Some
is well-recorded -
Dire Straits, for example. But most isn't. I love rock music, but it isn't the greatest reference material for listening tests, IMHO. Smaller Jazz ensembles work for me. A lot of jazz is very well recorded. A good jazz recording of a stand-up bass would be good for checking your bass SQ for music. The reality is though, that there isn't any very deep bass in music - except pipe organ.
That can rattle your walls, if you have a good sub. If your system is for music only, testing with music frequencies is fine. If this is a HT setup and you like action movies, you'll need some test tones to check the truly low frequencies.
Good luck!