How far can room treatments solve boomy bass?

Good question, i have tried them all. What i ment was, hope he does not fall for a sales-hype that can come in many different suggestions. I also ment, that an idiot must realize reading a graph, that not many things can solve bass modes of significant + db's. I can measure a somewhat result of a bass panel absorber. What they do for a low bass peak mode is pretty much nothing. That is raw fact. A XTZ RA pro II cost no more than a rather cheap power chord. Such kit's did cost alot a few years ago. Don't rely on things you can't verify. There are to many vested crooks wishing to earn your cash. When i mention this cable soloution, it is actually a suggestion i was getting from a manufacturer. He was so into this i began to wonder if i could walk on water buying a set of his magic cables. Ah, you get the point. I suggest the OP try to mail Richard Bird at Rives and also Gik acoustics, just to see what responses he'll get. Both companies are very nice. From this point he can figure himself what to do. As mention and to repeat myself, the RA pro II is not to throw money for the pigs. It is a good way to actually see, understand and learn what to do.

Mechans, ofcourse. Back off a few years or more, such programs (complete kits) was very much more expensive and not as good. Not to to mention, as easy to use. The XTZ is advanced and great quality for a more than a resonable cost all new. This is also why many companies could rely on the fact, we could not check facts for ourselves, but rather relied on their sales-hype.

If one implements the wrong solution for an acoustic problem, then yeah, it's not going to work very well. But if I have a spike at (say) 43 Hz, and I install a tuned acoustic filter (Helmholz, etc.) designed for maximum absorption at 43 Hz, and things don't get better, then I either need

a) better placement
b) more filter

This isn't voodoo.

Nope, it should work. It's probably more of *b.
I used Varitune V-6 before and more of them, absorbed more db. Using the PARC, i just deduct more level, if needed. I also have 43Hz as a major peak

For OP, if you can measure your room with XTZ RA pro II, you can order special tuned Scopus Traps. This way (measured), you can start off buying only several Scopus to start off ridding the modes. Measuring helps you and help Gik with two things.
1) Determine at what frequency or frequencies you'll have the peaks.
2) The actual level in db the modes are.

If you do not measure, you'll have to guess and might end up absorbing less specific which in turn, will not help you ridding the actual mode at that degree you'll need.
When measured and you know the actual level in db of the mode(s). You can tell that to Gik and they will be able to tell you how many panels you'll need. Also, custom make them to absorb (better/more) at this or these frequencies.

When that is done and installed, you can easily determine if you feel more panels are needed. Maybe not!
Ceiling usually is a problem. Concrete walls and ceiling can give a harder reflection. Some usually blame cables for being bright, this can be due to the ceiling, walls. Glass (windows) are even worse.
http://www.gikacoustics.com/gik_scopus_tuned_traps.html
I use 242 in the ceiling, but if i had bought now i had bought GridFusors. Placement in ceiling you can spot doing like this. Sit in your listening position, have a friend walking at each side between speakers and where you sit. When you see left speaker at left side that is first reflection, when you'll see right speaker at left side it is second reflection. Ofcourse, you can do same at right side of listening position. In line between these sides, the ceiling reflections are located. Now you can determine where to put ceiling panels aswell as side reflection panels. For example, in my room the ceiling reflection has a huge impact.
http://www.gikacoustics.com/gik_gridfusor_acoustic_diffusors.html

Bass boom:
For instance, i have a big mode at 43Hz (around 19db!).
So for me it had been wise to try Scopus and ask Gik to specially tune a kit of absorbers as close as possible to absorb at 43Hz. This i had never known if i couldn't measure my room. I can measure in corners and listening position where modes actually develops and at what specific frequencies. I can also see where in the range i have big dips (opposite to modes/peaks).