Best Subwoofer for B&W 805s Speakers

As many might know the B&W 805s speakers lack bass and I am trying to find a subwoofer under $1000 that would integrate well these speakers. I've been doing a lot of research on the web and there are too many choices out there (SVS, HSU, AV123, EPIK...) and I can't seem to decide. This is srictly for a 2 channel stereo system so no HT. My Equipment is all Rotel. Any suggestions? Thanks.
REL Storm III @ $900 to $1,000 on the used market. Very musical with a seamless presentation... offering a high degree of flexibility as far as connection options and adjustability. I had previously owned four other subs, including two from Velodyne, one from Atlantic Technologies and an old Yamaha sub, and the REL bested them all by a wide margin.

I would have never sold my REL, except for the fact that my Dynaudio C4's don't need a subwoofer, and I plan on keeping them for a long while, and I used the proceeds from the sub for some NOS tubes. If I'm ever in the need for another sub, REL would be at the top of my list.
Check out the subwoofer tests. It might help to limit the choices.
Thanks, I'll keep the REL in mind, I know they are very musical since this is at the top end of my budget I was wondering if anyone has had any experience/good results with something a even less costly?
The B&W ASW610 (retails for $1000) gets high marks from Stereophile. Used, you may alos look at Velodynes SPL series.
Consider the REL T series. I have just added a T-2 to my system with excellent results. There is a T-1 listed today .
I disagree- with the right amplification the 805s do NOT lack bass! Try using better upstream components- good CD player will definitely make a significant difference and use solid state (rather than tubby tube amp) amp with a adequate current delivery. For even better results- biwire the speakers. I have used with a Marantz PM11S1 and the bass is very rich and tight.
I disagree- with the right amplification the 805s do NOT lack bass!
Maybe tucked in a corner on the floor. :-) B&W's specs are pretty clear (49Hz - 22kHz ±3dB on reference axis) and that 49Hz is probably optimistic. It's the normal limitations of a small box with a small driver. The amp won't improve the situation.
I've been using a Velodyne DD-10 with my 805's for
a couple of years now. I'm pretty happy with it and
the built in room correction software is nice to have.
I think the 805's have great bass. Very tight and defined
but they lack depth. A quality sub will go a long
way toward brigning out the best of these monitors.

The amp I have is the Rotel RB 1080 and Rotel RCD 1072 CD player, are these components not considered upstream. Also I have bi-wired the speakers. The Velodyne DD series would be my ultimate choice but a bit too pricey for me. I am seriously considering a AV123 MFW 15 now.
I think your electronics are fine. Personally, I wouldn't bother with biwiring the speakers, but it doesn't hurt anything.

Depending on the size of your room, I'd seriously consider this or this

If you can find the APR/MAY 2008 issue of The Sensible Sound, you'll find a review of the SVS SB12-Plus. It's sealed and has a crossover builtin for high-passing your speakers for $700. I intend on using this sub in my office system.
I am seriously considering a AV123 MFW 15 now.

You'll need a separate crossover with that sub since it doesn't provide one. The NHT X2 filter sells for $350 so factor that into your budget.
I never knew I needed a crossover, I guess that shows my inexperience. The SVS SB12 plus is one of the first subs I looked at, the word on the street I got was SVS was better for HT than music, the HSU(VTF 2.3 or 3.3) was better for music. How do I know whether I need a crossover with a sub for future reference? I already tried out the Martin Logan Dynamo and it didn't sound too bad. I'd like to thanks everyone for their input.
Fast, a good clean sub works equally well for both music and HT. SVS subs play low, loud and clean as their measurements show -- in the deep bass the group delay is on the high side. Find the most recent Stereophile and read Larry Greenhill's review of the PB13-Ultra.

Regarding a crossover (or bass management controller as it's sometimes called for multichannel systems)... As you'd expect, you'll get differring opinions as to whether or not you should use or need one. The fact is that woofers produce distortion as the frequency decreases or the SPL increases. Just look at the sub distortion measurements. For example, the REL T1 to make 30Hz at 90db produces 6% distortion, at 25Hz at 90dB it's 22% distortion; raise the level to 100dB and you get 14% at 30Hz and well it can't make it to 25Hz at that level.

Subs have 10", 12" or larger drivers (in fairly large boxes), what happens when a 6.5" driver (in a smallish box) is asked to produce bass? B&W says your 805's distortion is less than 1% from 100HZ on up at 90dB at 1 meter (not 2 meter as the subs are tested so this makes the values look better than they really are). What do you think the distortion is at 50Hz at 90dB? Maybe 5%, maybe more, maybe a lot more.

The idea behind using a crossover is to protect the main speakers from bass frequencies and route those frequencies to the subwoofer which is designed to handle them. The speaker system will produce much lower distortion levels this way. Purists will say that adding another piece of electronics to the chain only mucks up the signal. I agree that the crossover may add maybe 0.5% distortion to the signal, but compared to what the main speakers will do without a crossover it's a no brainer to me.

As a side benefit you gain some headroom in the amp by removing a portion of the audio band it has to handle. You are actively bi-amping with the amp in the subwoofer.

Hope this helps a little and good luck in picking a sub. You will need an SPL meter and bass test tones to calibrate it.
Thanks for the explanation Bob. You have me leaning towards the SB12.
Anyone have any feedback on the Robert Acoustics Vigor? They have B-stocks on sale for $549.