How To Add A Sub To B&W N802's

I am thinking about buying one of the B&W 800 series subwoofers to my N802's. I honestly know nothing about how to go about this or if it is even a good idea? I thought about upgrading to bigger B&W's like the 801's but thought this might be an easier and cheaper route. Any advice on this at all?
JL F113 or SVS PB13 Ultra are worth checking out.
Thanks I am interested in the 800 series of subs from b&w but I do not even know if it is a good idea to add a sub or if it is how to go about it. I pretty much got the sub picked out already.
I had N801's and now have Signature 800's. I use a JL Audio F113 subwoofer. Word on the street is that it is much better than the B&W sub. I love it. Extremely tight bass and blends well with the mains.

In my experience an upgrade to the bigger B&W will probably not give you the increase that you are looking for. Take that with a grain of salt as I have a very large room. At the same time, I do not listen very loud (maybe 75 to 85 db at the most). After adjustment, the sub blends in nicely and adds some warmth.
Assuming you plan to use bass management (TACT, PARC or some such device for room modes) then go for it. I am not familiar with B&W subs and they may include thus feature.

Otherwise you may find room modes iompressive but too much for good two channel listening.
I use 803D mains and a B&W ASW825 sub with HTM2 center and 805s for the rears. This works very well for HT, but I run only the 803D for stereo and have been very satisfied with the base. Perhaps some speaker positioning or room adjustment/treatment could help? Also the B&W is a bit of a difficult load, especially the big guys like you have- maybe a bigger amp?
I use a REL Stentor III with my 802N's. Extremely fast and musical sub. B&W subs are really not what you would want.
yeah I feel like I am missing that slam. I listen at very loud levels and my room is fairly big but who knows how long I will be in the same room. I read it is a good idea to get two subs for stereo listening but I really don't think I can do that finincially right now. I will only be using this for streo music by the way in case that helps with the replies. This is kind if embarrasing but I don't even know how you would hook up a sub, do you hook it up to the preamp or what?
Shadorne I do not even know what bass managment is. Honestly I never even though about a sub till recently but at first it seemed like a good idea instead of upgrading the speakers which would be very costly. The sub I am looking at retails at $3500.
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The simplest may be to get a Y adaptor to take your preamp outs to the sub and your mains.

Since you have large floorstanders then I would run them full range and use the sub to fill in just the bottom octave.

The issue you will face is room modes....large peaks and nulls in the bass response below 100 Hz due to the most rooms you end up with boomy bass and two or three peaks that need an EQ notch filter to bring then down and lots of acoustic treatment to try to keep the bass even above 100 Hz. Look up Rives PARC on their website for info.

It would be a big mistake to get a $3500 sub and not check your setup for room modes and try to EQ it a bit to get something a bit smoother....
yes this is confusing but I appreciate the replies :(

that does sound sensible to me about the sub just filling in the bottom.
To answer your quesiton, it is a good idea to add a sub if you are looking for more slam. They give it. Before you go and spend $3500 on one, it might also be a good idea to do a little investigating. There are some great companys out there who do nothing but build subwoofers and may beat out the B&W for much less. Some have already been mentioned, such as JL and Rel. Some others to read up on are Hsu, SVS, and Epik lines. Hooking them up will not be difficult as they have numerous connections. If you have a subwoofer out on your preamp, that would be the easiest. You can also add a second pair of speaker wires from the left or right channel posts of your amp to the sub. The Rels have their own dedicated cable just for that. Good luck
I use a B&W ASW 850 sub with the Velodyne SMS-1 sub controller. I have B&W 800's with this setup and run them full range. I cross the sub at 40hz and have experimented with al the options on the sub EQ to arrive to where I am at right now. The bass at the sitting position is just right and not boomy. It will take some time to dial in a sub. I have used several subs and to me it seems that you can get almost any sub over 12" to blend fairly easy, especially the sealed design subs. I chose the B&W ASW 85o sub for it's deep bass response, 14hz and it fits well into my listening space.
I been looking around and it seems a used AWS850 will be much cheaper and do about the same as the 855
sorry ASW850 not AWS (typo)