How far can room treatments solve boomy bass?

Walls create bass peaks. They amplify frequency (and multiples) that is f=1135/(2*L) where 1135 is speed of sound in ft/s and L is distance between front and rear wall (2 is for traveling back and forth in order to add). Larger room should help but you can also use sound absorbing panels. Normally they work the best when they are spaced from rear wall by either 1/2 or 1/4 (don't remember) of the wave (eqv. to frequency amplified by room). In my room it is not even possible and I'm forced to put them on the wall. I bought John Manville 817 rigid 2'x4'x2" (faced) fiberglass panels and glued them to fiber boards. I will stretch fabric on them and hang on the wall. Look at sound absorption coefficients: http://www.jm.com/insulation/performance_materials/products/ci9_800series_spin-glas.pdf

At 125Hz it is 0.38 - still OK but less dense (and more common) 814 is only 0.24. It is basically density (weight) of the panel that is amount of fiberglass they used. 4" panels would be ideal but I don't have space for them and there is, of course, WAF. Forget about curtains, blankets etc. If you can hear bass thru it then it won't stop bass reflections.

Zmanastronomy, I've tried it but it has to be very loose fabric and it also reduces bass punch. I had more room resonances with previous speakers (two 6" woofers) than new (two 8" woofers). It could be that larger woofers deliver more sound direct (larger area) or it is just better speaker less prone to interaction with the room. Some of the smaller speakers with ports tuned to extend bass have hump on the multiples of port frequency - visible on frequency response chart.

Martykl, Yes taming low bass might be difficult but it is doable. My panels won't work well below 125Hz, according to datasheet, but 4" panel would. I hope that putting 2" panels on opposite walls will increase damping at low frequencies. I will know more after my panels are up.

EQ is not a magic bullet because it does nothing to long decay of boomy bass. That's perhaps why they spend fortune in recording studios and concert halls on acoustic treatments before playing with equalizer.

I would try speaker positioning, try different electronics and cables, apply acoustic treatments and then EQ. Boomy bass in my room got better with different cables to be further improved with class D amp to finally become more even with power conditioner. All this before room treatments.

Martykl, It is not only issue of loudness but also extended decay time. I also feel that additional pieces of electronics in the signal path don't improve clarity.

I agree with Ja2austintx assessment: fix the room, then decide.