Do I need a subwoofer?

For my AV system I'm using two B&W 608 small subs along with  B&W 603 S2 towers, B&W Center channel and B&W 607 surrounds to make a 5.2 AV system.

This is completely separate from my 2 channel music system.

This little 5.2 manages to seamlessly meet AV surround stage for the most demanding sound tracks.  Point is 2 small subs are more than sufficient in a large room and easy to set up.

Hello olfac87, Like you I found myself back in the research game about 12 months ago. I had to start from scratch and didn't even know what a dac was. Imop a sub can enhance any system and enjoy one myself. A friend once said to me "for food to taste good when cooking you have to f...with it." Again imop if you add a sub you should be committed to being an active participant with your system and willing to adjust levels depending on the production of the recording. If you do this it can be most pleasurable.

I just added a 2nd SVS SB2000 to my system and it's so much more balanced now. I'm running them as a stereo pair right next to my mains. I'm able to run them at a lower power compared to the one single so it doesn't excite the room modes nearly as much and still fills in a lot more evenly across the board with easily reaching into the upper teens . It takes a huge amount of the congestion out of the lower octaves that I never knew were there previously. As for your choice, I'd recommend sealed are definitely the way to go unless you have the space to do full open baffle servo subs.

There is a lot of information in the bottom octaves that are related to soundstage and ambience, and other spatial cues.

As decently low as those B&W,s go on their own, adding good quality subs, will create a more open, larger soundstage, than without.

This tends to be more obvious with music that is recorded, with all musicians playing at the same time, and in the same acoustic space, such as: classical or jazz. But all types of decently recorded music will benefit

I would use at least 2 subwoofers for the best ultra low bass that even the B and W's are missing. SVS is a decent sub, but I would not get anything less than the 3000 series and I'm partial to sealed or servo controlled subs. You can get SVS with a return window in case you don't like them. What is your room size? In general the more subs you have the fewer the null or dead zones in the bass. I agree with the need for room treatment.

@erik_squires That was a nicely written piece. Very informative. Room treatments has been something I have lacked in.

This comes up so often I wrote a post about it:

All - this is super helpful. I am enjoying being back in the research game after years doing nothing to my system (looking to replace my preamp, too - that's a different story). The SVS line looks like a good place to start.

Those 15" woofers ought to be giving you plenty without potentially adding mud.

Perhaps, if space allows, go for the non-directional multi-sub ’swarm’ solution. Then you add a room filling BASE of bass, which transcends up to directional bass from those 15" woofer’s emanation of low primary and their overtones which reinforce directional cues.

You might think: add the sub(s) ONLY for Video. My small HT, not what you are dealing with, I have a single self-powered sub, I keep the crossover set low, essentially just add something for Jurassic Park Dinosaur Stomp, not aware of it unless it is off.

On for music, no room or budget for swarm, a stereo pair of self-powered subs, no ports (or front port only), located adjacent to the mains.

In addition to adding bass, properly set up subs will also greatly improve imaging and expand the soundstage.  I’d recommend trying a pair of SVS SB1000 Pro subs you can get for under $1000 (they were running a sale recently but not sure if it’s still going) that are relatively small but will still get you down to an honest 20Hz and also offer integration software to help you get them dialed in properly.  And yes, you want two, not one sub — huge improvement.  SVS offers a generous and truly risk-free, in-home trial so if they don’t transform your system you can simply return them but highly doubt you will.  Hope this helps, and best of luck. 

Actually running three subs would be best.  Every room has cancelations from reflections and by using multiple subwoofers you can overcome the room issues.

The good news is that doesn't require the most expensive subs and they really only fill in for room acoustics.

http://www.gedlee.com/Papers/multiple%20subs.pdf

@russ69  Someone said with stereo subs I should do two versus the one big one I have now? They seem a lot smaller, too, which would make the wife happy. If I am understanding what stereo subs are (did a quick Google search).

The B&Ws will be doing most of the work for the bass you like to hear but subs will fill in that lower frequency weight that subs do well. Stereo subs facing forward are the way to go if you don't want to spend the money on a set of woofer towers. It's up to you as the B&Ws are still pretty good with subs.