Raul,
Before reading your post in the link you supplied, I had already heard and described the "unexpected to me" influences that the dual-REL subs have on my system’s sound, perhaps using somewhat different and less precise descriptives than you do in that post.
Like you say there:
"- better quality low bass ( you can have at least one more octave ) and mid bass "
"- An improvement in the soundstage reproduction in all parameters: deep, front/side location, wide of the stage, etc..."
In my system, I would add something like:
"-an improvement in imaging, air, and a sense of infinite space around the performers and within the soundstage itself"
The other key point you bring to that post is improvement resulting from relieving the main speakers and amplifiers of the difficult lower-octave reproduction challenge. I understand this to imply introducing an external crossover into the signal path of the main system (if I am mistaken, please correct me). I do not yet do this, as it concerns me regarding tampering with Jim Thiel’s ingenius 1st-order crossover and the (extremely) low probability of my feeble speaker design skills bettering Jim’s in this regard. A mental picture of Jim turning over in his grave comes to mind (I assure everyone that I mean absolutely no disrespect or levity to Jim’s passing).
A very good friend of mine has a stratospherically high-performance and high-priced system. He recently wrote me singing the praises of the room-correction software that he acquired with/for his dual JL Audio Gotham subs. He only uses digital sources, asserting that "turntables do add a certain pleasing warmth to the sound, but are ultimately inferior in accurate high-performance sound reproduction". We agree to (strongly) disagree on this for the sake of our continued friendship.
I would think that, with the almost unimaginable capability that today’s computers have to capture, analyze, and process billions (trillions?) of data points that this would indeed be the way to go re: add-on crossovers compared to the analog domain ones I have used (the then-SOTA external crossovers provided with the Apogee Divas I set up and meticulously tuned in my installer days), but I EMPHATICALLY REFUSE TO DIGITIZE MY BELOVED ANALOG SIGNAL SOURCE!!
I submit for your consideration (very Rod Serlingish, don’t you think) that some of the improvements you attribute to implementing additional crossovers are perhaps due more to the magical effect of loading the listening room with gobs of hyper-LF sound pressure that works in effect to "relieve the ROOM of the difficult lower-octave reproduction challenge". This of course assumes (and we know what happens when we do that) that the subject amplifiers and speakers are of sufficient quality to handle the task of accurately reproducing the lower octaves of our musical content (I admit to having an extreme aversion to most organ music so I may be exposed there) .
Dave
