Are big subwoofers viable for 2 channel music?

Rythmik. At least look into them.

I have a medium/ large area and use 2 HP Rythmik 15" subs.  They do anything you ask them to do. High damping acts like a speaker. Start and stop on a dime. I believe it's the servo design. You wouldn't know I have subs until they're called upon. I use them for music and movies. Actually, you still dont know the subs are there, but I dont have speakers that go that low. They are absolutely seamless. 

I did have my audio set up by a pro. Took 5-6 hours for HT setup, but it can definitely be seemless.

I suggest 2 f18s for your room, then if needed, you can always get 2 more. I doubt you'll need more. You do get a 2 sub discount. 

Good luck
 

big_greg and bdp24,

I agree with you both that four independent subs allows for maximum adjustability and flexibility. I know from personal experience, however, that this level of adjustability and flexibility is not required for excellent bass performance results using the Swarm system.
Audio Kinesis does state that bass performance can possibly be improved by inverting the phase on one of the four subs in some rooms but I noticed no improvement in my room with any of the subs having their phase reversed. Also, their suggested method of phase inversion is simply to reverse the pos. and neg. wires at the sub terminal connections.

big_greg: "I have one sitting just a few feet from my listening position and another on the far side of the room. It doesn’t seem that having them all at the same level would be a good thing."

My listening seat is positioned along my rear wall between two of the four subs, one positioned about 8’ away along the left side wall and the other about 3’ away along the right side wall. The two other subs are both about 20’ away along the front wall. All are operated in mono mode and at identical volumes. I perceive the bass on both music and HT as coming from the front of the room and never perceive the bass as coming from the subs nearest me to the right and left of my listening chair.
I believe this is due to the efficacy of the scientifically proven DBA concept that works exceptionally well in virtually any room and with any pair of main speakers.
This DBA concept takes advantage of both how bass sound waves behave in domestic sized rooms and the accumulated psycho-acoustic knowledge concerning how humans perceive sound at various frequencies. I can state with certainty that the 4-sub DBA concept works exceptionally well in my room and I believe it will work equally well in virtually any other room.

Tim

The PSA sub appears to be geared more towards home theater.

Hey @big_greg and @ smodtactical

That couldn't be farther from the truth. I'm here to tell you that psa subs have a uncanny ability to disappear with sheer musicality when they're playing music with any gear at any price point. Tom Vodhanel of psa doesn't even advertise his speakers. They are sold by word of mouth. That should speak volumes. Remember Tom Vodhanel was the V in SVS subs. My PSA V1801's are an astounding value and I use them primarily for music.

I gotta go with millercarbon on this one. Let's say you've got the biggest and baddest sub on the planet, you're only gonna turn the gain up what 2,3 or 4 maybe? Because you're going to set the gain and volume to what's comfortable to you and you listening pleasure right?

Guess what happens when you add 1 more sub to equal 2? And then you add 2 more let's say at the back of your listening room, mancave, theater room or whatever - spread out somewhat for a total of 4. Suddenly you're enveloped by smooth bass all around you where you actually don't have to turn the gain on your bass subs up much at all to get the distributed array benefits of beautiful bass.

It's just another way of thinking (or technique) when using subs. It didn't click for me for a long time, but when it did...You don't need monster subs like the PSA S7201 to get the best bass. Although, 2 PSA S701's equal 4 subs and the effect of 4 subs will be realized there too!