Hi to everybody,
Yeah as a lot of people said, those DSPs won't correct the big problems of a room.
I went with the acoustic treatments first, trying to build everything myself based on what i found on the web, and this way it is pretty cheap (just a high amount of time...which is something quite expensive i realized later!).
But, my lack of full knowledge with room acoustics ended with a pretty usable room, but with a few remaining problems (the most problematic being a 3-4 dB boost around 85Hz).
As i had already too much delay in the building process, i decided to first try to work with the room as it was, playing with monitor placement.
But i could not find a way.
So i tried a unit from Tact Audio, which is aimed at the audiophile market. It was one of the first all digital preamp to include "room correction" features.
I was hoping just to remove theses few problems with it, but when i heard the result after having set up the correction (that was a bit cumbersome due to their far-from-perfect set-up software), i quite fell of my chair!
This thing also aligns the speakers in the time domain (the correction being more of a FFT impulse and some small delays, not just a parametric/graphic EQ).
The stereo image/depth was also way more stable, and of course, the low end problem had disappeared.
Another thing that i found very useful is the fact that you can set several presets, ans just recall them with the remote controller. That way i did a correction for the sofa behind the mixing position, which while not giving a result as good as what i got at the console, is much much better than without the correction.
But i doubt that would be usable if i'd done no treatments before...