35Hz - 25kHz -- A Partial 'Purist'?

I'm with you Stehno. If you enjoy music in which low bass content reproduced in proper scale and dynamic balance with the rest of the music's content is important, I think it is better to have the bass and put up with a some discontinuity than to forsake the bass altogether. However, I would not (and do not) compromise the output quality of my main speakers by using the crossovers in powered subwoofers. Adding more bass "underneath" my main speakers' output is the path I have taken (using RELs), and I am much the happier for it. Yeah, I can hear the subwoofers, now and then, but for me the good far outweighs the bad.

the sub i'm looking for HAS TO offer a seemless intergrated sound...if i "hear " the sub while listening to the music i don't want it in my system...i'll do without...howevere the brand new sub line from FOCAL the 11WX 13WX 15WX seems to be the one up to the job..i'll use my out on my JADIS to drive a sub amp, any suggestions on superior sub amps? as well should i go single 13 , 15 or dual 11's?

Tweekerman, If you've got to do it, then use a sub that has a driver with a very low Fs(resonant frequency). Usually the larger size drivers. Large phase shifts appear around the Fs, and can extend into the listening range. Fs should be about 15Hz or lower if possible. Then, actively cross out the sub as low as possible to avoid contamination of the lower mids/upper bass. If you have a closed box main speaker,the lows will roll off at about 12db/octave below the Fs of your woofer. If you have a vented enclosure, the lows will roll off rather steeply at 24db/octave. Allow the mains to roll of naturally with no cross out. Set your sub crossover point to 1 octave below the mains Fs and use a 12db slope on the sub crossover if you have sealed box mains. If you have vented mains, set the crossover point at 1/2 octave below the Fs of the PORT, and use a 24db/octave slope on the sub crossover. By matching the rolloff points at these points, the slopes will intersect halfway beween, and the additive effects of the two rolloffs intersecting will give a theoretically smooth transition. This is just a starting point and may require adjustment if you hear a hole or a peak. If you don't know the Fs, then use the 3db down point of your mains' response curve as a guide.

What happens techinically if you add a sub? And also, what is the proper way to add a sub? If I plug in the powered sub to a "regular out" on the pre-amp, does the signal somehow only send the lower frequencies to the sub, thereby reducing the "load" on the main speakers woofers?, or is the "signal strength" going out of the pre-amp to both the main amp and the sub-woofer relatively the same strength?

The situation you describe would send the same frequencies or signal strength to sub as to your mains.

In my case, my pre has RCA and XLR outs. I use XLR outs to the amp and RCA outs to the sub. The filters in sub filter out the frequencies you've desired not to have the sub reproduce.