Room modes are hijacking my music

My listening room is resonating in the 60-300 Hz range. I've been living with this boominess for quite a while, but I thought it was just the nature of a ported speaker (Dahlquist DQ-30). In an effort to tame it, I attenuated power to the woofers via biamping, but the results were spotty and less than perfect. Some material needed more attenuation, while others needed less. It was a pain to go through this when I just wanted sit down and listen to music.

Well, I recently picked up a pair of Alon Model I's which have an 8 inch acoustic suspension woofer, but the problem continued. I was puzzled at first because I knew the Alon's shouldn't sound like this. That's when it dawned on me that it wasn't the speaker, but the room. So I started playing with an equalizer to level out the bass and the results have been nothing short of staggering. By reducing the signal as much as 8-10 dB at 125 Hz and gradually flatting the dip back to zero at 32 Hz and 500 Hz, I've completely eliminated the boom and now hear deep tight bass. The improvement is stunning and the speakers sound amazing! I can't emphasize this enough. Of course, I don't want an equalizer in my signal path! So, I'm faced with the task of taming my room with absorption materials. I'm not thrilled about this. Decorating my walls with R50 insulation blocks dressed in some fabric is not my idea of modern art, but I don't see any other alternative. How have others dealt with this problem? I can't (and won't) ignore it.

I've learned a big lesson here. We're hard wired into thinking that upgrades will improve our system. We're so focused on the equipment that we often overlook abstract considerations. I'm generalizing, but you get the idea. Most people throw money at their system hoping it will improve.

FWIW, my room dimensions: 15' x 17' x 9'

Insights and suggestions are warmly welcomed.

Mark