Do I need a subwoofer?

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.

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.

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

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

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.