Do you use a Subwoofer when listening to stereo?

I agree with @noble100 
If your speakers are generally of the full range variety, no need to add an additional electronic crossover to the mix. KISS applies here, less electronic artifacts, the better.

Oz

it is not fine to run satellites full range while adding subs for three reasons. First is you miss the opportunity to lower distortion and increase head room significantly in the satellites. Second is you make integration much more difficult. You are down where the wavelengths are over 10 feet up to 30 feet. Unless you are using digital bass management matching phase and time are difficult, usually by trial and error moving the speakers and perhaps by using a phase control on the sub. Without a two way crossover there will be more overlap making the problem worse.

I get the part about distortion and headroom in the mains (which you are calling 'satellites'). Its an issue that has concerned me. But as far as getting matching time and phase, below 80Hz its simply not a thing. The reason why has been explained here several times so I'm not going to repeat it.

I ordered a pair of the Swarm subs to supplement my Classic Audio Loudspeakers which are flat to 20 Hz. The problem is I have a standing wave at the listening chair and too much bass elsewhere. So I only need two subs and I got Swarms since they are designed to operate inside the room boundary effect. I need them to be against the walls out of the way. Here are the instructions Duke sent along. When you look at his comments, its obvious that all the things that you are commenting about are on his mind as well, but are easily solved without resorting to DSP:

You MIGHT try this: Start the subwoofer amp's phase control at 90 degrees (that may change later in the process), and wire the two subs
in opposite polarity from one another. This will tend to prevent them from making the low bass region too loud, while they are improving
the in-room bass smoothness. If the two Swarm subs are to the left and right of the listening area, this may also increase the sense of
immersion in a large acoustic space.

I normally leave the 18 Hz protective highpass filter ON, but that's up to you. Also, have the "Bass Boost" off. These controls are
on the back of the amp.

As a suggested starting point, going from left to right across the front of the subwoofer amp,
first the EQ: Frequency 18; Bandwidth .1; Level "0". This effectively turns the EQ "off", so it's in reserve in case we need it.

Next the other controls: Phase 90 degrees; Frequency 10:00 (about 75 Hz); and Gain at 11:00.

If you are going to be "dialing in" the subs by ear, here is the sequence of events that I suggest (you can also use this sequence
if you're using measurements):

1. First, adjust the Gain for best sound. This is the control which will make the most difference.

2. Next, adjust the Frequency. This will make the next most difference.

3. Cycle back through Gain and Frequency at least once.

4. Adjust the Phase. This will make the least amount of difference.

5. If there is too much bottom end, try plugging one port, and then unplug that one and try plugging the other.
If it's still too much, plug 'em both.

6. If there is not enough at the bottom end, try putting both subs back in "normal" polarity. If you lose smoothness from doing
this, go back to having one in reversed polarity and plan on using the single band of parametric EQ.

7. If there is still a problem area, OR if you need to boost the very bottom end, use the parametric EQ. Unless you have
measurements, expect some trial-and-error.

8. Cycle back through Gain - Frequency - Phase one last time.

It may still take several days before the Gain is dialed in exactly right. There are two reasons for this. First, the ear is
especially sensitive to changes in SPL in the bass region, so a small change makes a larger perceptual difference than you would
have expected. Second, the little knobs on that Dayton Audio amplifier are maddeningly small, so it's real easy to move the knob
more than you intended.

Having had some exposure to only marginally integrated subs, leaves me to keep my wishes clear of any subs rocking my guts. (I'm not into 'thunder and lighting' AV shows either.) So, 'Horses for courses' I'd say.

@justmetoo — I’d say you’d do well to go hear a system with well integrated subs as you’re completely missing (and mis-categorizing) the benefits they can provide.  And subs could also actually help alleviate the slight bass overload issue you’re experiencing.  Keep an open mind on this and you might be rewarded greatly. 

It is all a personal taste.  Some do like it, some do not.  I do.

@ozzy62 --

...
If your speakers are generally of the full range variety, no need to add an additional electronic crossover to the mix. KISS applies here, less electronic artifacts, the better.

It depends on the specific set-up and quality of the digital cross-over (which needn’t be expensive per se); where well-chosen it can, potentially, lead to an even better outcome with the main speakers high-passed. For this to have the best effect (i.e.: a HP on the mains) it seems generally accepted that a cross-over no lower than ~80Hz leads to the best outcome in taking advantage of relieving the mains (+ their amp(s)) from the central to lower bass, leading to 6-10dB more headroom and a likely cleaner, more effortless reproduction (with 2-way main speakers the benefits of a HP may be even more pronounced as this more obviously affects midrange cleanliness).

Such an approach however may call for added attention in regards to subs placement being in symmetry with the mains, as directivity will have a bigger say with a chosen, higher XO-frequency. Theory may dictate it’s difficult to nigh on impossible to localize bass even with a XO up to 100Hz or a bit higher to the mains, but when practically experimented with I’ve found placing a pair of subs symmetrical to the mains is very beneficial, even when crossed into the 70’s.

This type of set-up with two symmetrically placed subs would still be compatible as a future DBA, as additional subs could be crossed lower and placed more freely to best take advantage of smoothing out room modes, or where ever interior decoration may dictate them to be placed. In fact that’s what I may intend at a future point, adding to my existing two subs.

For all its apparent prowess a DBA set-up as configured with the mains run full-range doesn’t take advantage of the potential gains to be had with a HP on the mains and a higher XO here. Added component complexity in the form of a quality digital XO - while justified, to my ears, run in the signal chain over passive speakers - mayn’t be so in every case; my set-up is fully active via separate components, and as such the digital cross-over used is, by necessity, in the signal chain to begin with acting as the XO (without ANY passive filter components) for both the mains and subs, and so a high-pass on the mains isn’t adding more physical components, but simply an extra high-pass digitally.