Proper subwoofer integration?

I have three different methods of passing the bass off to my subwoofers. My amp has DSP that allows me to set a crossover frequency from 40hz to about 200hz (just like an AV receiver), but I'm unsure about the db/octave slope of it's filer. I use JRiver Media Center which also has DSP functionality (it's crossover can be set to either 12db/octave or 24db/octave), and the subs themselves have low pass filters variable from 40hz up to about 180 or 200hz. The subs also have the ability to switch the filters off completely. Which one (or combination) of these filters should I be using? I'm thinking that a steep slope might be preferable so that there is a narrower frequency range in which both speakers and subs are playing. Right now I have my amp crossover set at 80hz, JRiver set to 80hz (12db/octave slope) and my subs set to 80hz. Do I really need all these filtering methods in use? How should I implement these options to get the cleanest transition from speakers to subs?
While this may sound over simplified - trial and error will be the best way to determine what works best.

Using all the filters in series, while it will no doubt result in a very steep cross-over slope, will most likely make integrating the sub difficult. Cross-overs effect phase and having all those filters in series can cause phase shifts which may complicate integration.

Slope and cross-over frequency depend on many things - main speaker placement, sub placement, room characteristics, main speaker and sub frequency and phase response, sub phase adjustability, amplitude (volume) etc.

I'd recommend starting with a simple slope and try a variety of locations and frequencies. Don't change too many variables at once otherwise identifying results can be difficult and misleading.

One of the best integrated subs I heard used a Rel sub with a pair of Martin Logan speakers. The speakers were set up about 1/3 out into the room and the sub was located to the right and just in front of the listening chair! The chair was located just shy of about 1/4 from the rear wall.

The sub completely filled out the entire music spectrum, not just the lower frequencies. It made the main speakers so much fuller and life like, detailed and balanced. It was if half of the speakers were turned off when the sub wasn't used! The cross over point was undetectable, the integration and acoustic results unbelievable!

So - experiment. Only change 1 variable at a time and use a variety of music you are familiar with to determine how well the sub integrates with and balances your system.

Hope this helps and best of luck, TJF.
Thank you Tjassoc. I will definitely take your advice. Luckily, I have already spent many hours adjusting speaker and sub placement and have found locations that render superb imaging and reasonably smooth bass output. It's amazing what having two subs does for bass in terms of smoothing out peaks and nulls. My subs are situated on opposite walls with one residing next to my left speaker and the other sitting just to the right of the listening position. I had a little trouble getting the levels matched as one sub is farther away than the other, but it was worth the effort. The listening seat is a seven foot sofa and virtually the entire length of it is the sweet spot! When your speakers are only 7.5 feet away that's not bad. Thanks again for your advice on the myriad of filter methods.
Glad to offer whatever help I could.