Do you use a Subwoofer when listening to stereo?

A. TWO Channel Mode/Use of Home Theater:

a1. AVR sends full frequency signals out front left and front right ONLY.

a2. no center, no surround, no sub signals from the AVR outputs.

a3. ALL Imaging is Phantom, created by AVR front left and front right. True whether you do or do not have a sub or two included in 2 channel mode. More below.

a4. programs that ’arrive’ in surround may/often sound better if you try/change to 2 Channel, thus more important than you might think.
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B. SUB(s) ON SURROUND ONLY (sub out, mains only for 2 channel (video or music).

b1. choose mains with enough bass when in 2 channel mode

b2. single sub, non-directional can more easily be successful when on only in surround mode

b3. easiest wiring, simply sub out of AVR to sub, done.
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C. SUB(s) ALWAYS ON (any Surround AND on for 2 channel).

c1. stereo pair of subs, directional, near mains

c2. all imaging is Phantom, any location of low bass fundamentals and overtones will reveal directionality, which you WANT.

c3. Now you need to take your AVR’s front left and front right to a CROSSOVER: ALWAYS send some to the sub(s); ALWAYS send the rest to the mains.

c4. Crossover can be separate component OR built into the sub(s). IF crossover is in the sub, then you have to get to the mains from the subs. This is another reason to use a stereo pair of subs located with the mains.

c5. Any crossover should be ADJUSTABLE for 5.1 or 2 channel

c6. self-powered subs produce the bass, which means the AVR’s amp and front speakers have an easier job to do

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D. SIZE OF MAINS SETTING

d1.Telling AVR the size of your mains effects surround modes only. It always sends full frequency out front left and front right in 2 channel mode.
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E. CENTER CHANNEL SPEAKER REQUIRED for ANY SURROUND MODE

e1. the programs coding, and the AVR's coding removes all the DESIGNATED audio information from the front speakers. Thus, a CENTER SPEAKER is definitely needed, no matter how good you mains are. You cannot make Phantom Center Dialog if the information does not exist in the front outputs.

e2. center channel is ALWAYS OFF during 2 Channel Mode, imaging from front and subs more important.

emergingsoul:
" noble100
thanks so much. awesome

so maybe setting up the speaker settings to large (rather than small) makes more sense so that it completely opens up the main speakers. Why bother restricting bass on mains, and then set the subwoofer separately via settings on back of cabinet..

The sub array setup may have merit in a larger room. My room is 12 x 16 with 7 1/2 ceilings. The extremely large asw 2000 from b&w with 12 inch driver set lower would seem more than adequate. I do need acoustic panels."

Hello emergingsoul,

     The choice of whether to operate one's main  L+R speakers full range. or restrict their low frequency output, should be based on the main speaker's efficiency, their rated bass extension, the specs of the amp driving them, whether a sub or subs are going to be employed and personal preferences.  
    In your case, for example, I believe your speakers are sufficiently efficient, have a sufficiently deep rated bass extension, your amp has sufficient power and current capacity and your going to employ at least 1 sub.  This means everything's a go for operating your main speakers full range and it just will depend on your personal preference. 
     I suggest you change your main speakers setting to large (rather than small), optimally position your sub in your room using the sub crawl method and setting your sub's volume and crossover frequency controls as low as possible with the bass still sounding very good to you.
      Then it's up to you concerning which system set up and configuration overall system sound quality you prefer.

Best wishes,
  Tim

@emergingsoul --

Do you use a Subwoofer when listening to stereo?

I do, very successfully, and god (or, that is: the DBA-inquisition) forbid only two of them. They're tapped horns taking up 20 cubic feet per cab, and tuned just below ~25Hz. Low-passed @83Hz, and symmetrically set up in relation to the main speakers. Smooth, enveloping and totally effortless bass.

I really think subs and surround for the home is nothing but a marketing gimmick. just distracting garbage. If I won lotto (gotta play first) and could hire a qualified team to design a system ground up using a stereo pair of speakers and subs maybe, but why not use the subwoofer/s money to get better mains? nah not even if I could do it for free.

If you are using a 2 way crossover rolling the 804s off say at 100Hz 24db/oct several things happen. You will increase the headroom of the satellite system. Essentially, it now has more power to spare.
You will drop the distortion levels of the 804's woofer. Everything else that woofer carries will be much cleaner. This all assumes at least two subwoofers adjusted correctly. Subwoofers set up incorrectly will more than likely make things worse. Unfortunately, in most systems subs are set up by trial and error. Then you have to deal with room acoustics which sub performance is very sensitive to. This is an important reason why multiple subs are required. I and others seem to have landed on 4 subwoofers as optimal. Ideally, you have digital control of crossovers, EQ and time and phase alignment. You measure the sub from several points in the room and overlay the curves. Peaks or troughs present at all locations are due to the subs performance and need to be corrected. Those that vary from one place to another are due to room modes. Correcting these is a waste of power and does not make anything sound better except at one specific point in the room. It will also add distortion due to higher loads on the driver and amplifier. If the bass does not sound good at the listening position you can start EQing the bass to neutralize some of the modes at the listening position.
Without digital bass management setting up the woofer depends on somebodies interpretation of the sound. Then, trial and error adjustments with the crossover and position of the speakers. It really is hit or miss. In many instances subwoofers should be avoided.