Esben, everyone, I have great news!!!.
Apparently, DRC outputs two files at the end of its calculations, one should be used as the "equalizing filter" (and the other is the impulse response of the system after correction, and it is useful to see the results achieved after correction), the thing is, I was convolving using the wrong file!. (It appears that my Rat Shack isn't THAT bad afterall).
Denis Sbragion was kind enough to go with me over all the possible problems that might have occurred. He told me that my Rat Shack mike really isn't up to the task of doing an accurate room measure for room correction, but it should sound much better than I've described. Also, according to some test signals that I've sent him, he told me that this mike is going to give me an overly bright image.
He was right, about everything. As soon as I started using the correct filter, the sound improved, dramatically. Also, it exhibits exactly what Denis said, an overly bright presentation, which really makes things sound compressed at the high frequency region. Anyway, I decided not to care for now about the high frequency region (since I can't do anything about it, yet), and test how my system (and especially, my room) sounds from the sweet spot.
My first reaction was, ASTONISHMENT, I kept saying to myself, "this can't be happening!", my room DISAPPEARED!. I first described it to Denis that it's like hearing my speakers in an unechoic room, it was an incredible experience. Later, Denis put it using better words, it's like the sound you get with headphones, only without the imaging being inside your brain (this is so true!!!). I have to warn you though, this stuff is addicting!, I've decided to bring all the songs which sounds less than decent in my room (especially those with heavy bass, like Marcus Miller), and was again, astounded. I actually prefered listening to the corrected signal, with those songs, even WITH the compressed high frquency response that I am getting. I still can't get over this experience. Some people often describe that after some changes they did in their system, it sounds like a veil had been removed from the speakers, well, in this case, it's like the room has been removed from the speakers!. I keep looking at the speakers, then at the room, then again at the speakers, then again at the walls, and just can't get over the experience that there is no apparent interaction between the two, the illusion is THAT good! (at least in my room, and your milage WILL vary, for better or worse, since no two rooms are the same).
I did notice a couple of things, like this process tax your amp to a certain degree (really depends on your room, I guess), but I have a 150WX2 amp, so this wasn't a big issue. Also, you really need to be in the listening spot, if you'll go too far, things start to sound funny.
Last but not least, Denis told me that sub calibration is not a problem, all I need is to let it work during both MLS recordings (for each speaker), and that DRC will do the rest. I can't wait to try it out tomorrow, using a 40hz cut off for the sub, and letting the mains go "large".
I'm going to buy a better mike next week, and if the higher frequencies problems are going to go away, I think we'll just have our first, truly "killer app" for the HTPC's audio domain. I can't thank Denis enough for all his hard work.
If you're going to try DRC for yourself, be patient, there are some bugs in the process that you might encounter (not with the DRC code itself, which doesn't have a graphical interface, yet, but more with the initial and final process).
I'm waiting until my mike is going to arrive next week, and once it will, if it will solve the problems I've mentioned (meaning, it get's my "audiophile approval", for what it's worth), I'm going to write a complete, step by step, updated guide (there is already one completely outdated guide), which is going to make things very easy for anyone who'll want to take advantage of this amazing tool. That's the least I could do for Denis.
Esben, the correction can only be done on the entire 20hz-20khz region. The correction will always be softer on the higher frequencies, and stronger on the lower frequencies, plus, you can set it manually to perform a much softer correction on the higher frequencies, but you won't be able to make it run only for the 20hz-200hz, for example. At least not with the current version. Believe me, if you mainly listen from your listening spot, and a good mic really solve the higher frequncies tonality, you'll have no problem going with a strong correction, all over the spectrum.
Reading my post again, I want to make sure one thing is clear:
The discussion in this forum raises a lot of possible ways to improve our listening quality. We try better cables, different sound cards, different output types (Kernel/Asio vs Kmixer's SRC), different software players etc. But, up to this point, even though I DO notice and appreciate some of the benefits gained from all the tweaks I've mentioed, the only time in my life I've experienced a real HUGE improvement in sound quality, was when I switched my several hunderds $ speakers, to a several thousands $ pair, this was the only time I experienced a trully dramatic change in sound quality, for the better. Until today.
Just wanted to clear that one. Again, it could be that my room has overly problematic acoustics (I didn't go and measure many other rooms, so I can't really compare), so you do understand that my results are highly dependant on that factor. But I'm sure some of you have worse rooms than mine, so I'm sure at least those guys are going to agree with every word I've written here today.
It's a good thing that DRC is a freeware, otherwise, some people would have surely made everything in their power to get me banned immediately, after this post, for marketing reasons.