Before buying the DEQX, you should read the portion of this journal concerning "Equalization . . . can't fix your room acoustics."
http://www.audioperfectionist.com/PDF%20files/journal1rl.pdfActually, I consider this a must-read for anyone contemplating audio purchases. I don't always agree with the author, but he provides food for thought.
Personally, the DECX does not interest me.
Stereophile likened it to a 4000-band equalizer, and another reviewer mentioned it has a 200-page instruction manual! This massive technical overload is the
antithesis of what I am looking for in music equipment, which is for the equipment to get the heck out of the way of the music! I don't think the DECX should even be thought of as a preamp--it's more of a magic box, the purpose of which is to compensate for the room it is in.
As the journal I linked to above explains, a microphone does not "hear" the way a human being does. My prediction is that the DECX is going to come up with a "perfect" sound according to the microphone that will
not be pleasing to your ear. Then you're going to have to make the choice of whether you should please your microphone and the computer analysis, or whether you should please you ear. If you choose your ear, you're back to where you could have been in the beginning--making sure your room itself has good acoustics. Room EQ can only disguise the problem, and at the high price of losing some of the music in the coverup.