Move your sub

Caught an Art Dudley video about moving your sub(s) from behind, beside or between your speakers to the seat end of the room. I moved my REL back so they are in the same plane as the listening position. Much better! Try it.

Can you post the link to the video please?

I brought mine from the corners of the front to nearly mid-room, flanking the main speakers and closer to the listening chair, and it has been superior.

It would seem that with the subs further out in the room they would need  to be played louder. 

Your optimizing the bass time arrival if subs near plane loudspeakers occupy you could also place behind listener or on sides if physical distance is near same as seated listener is from both speakers and sub. You could keep subs physical distance correct for time integration and pursue boundary re-enforcement that most subs require. Or use multiple sub systems this gives better measured response in most rooms lower distortion increases system output.

Placement depends to some extent on what subs you are using.  With the Vandersteen 2wq subs that I use, I need to keep them near each speaker as the subs reproduce frequencies high enough to affect imaging.
Proper sub integration starts with the room position that gives the smoothest response as measured at the listening position.  For my sub it happened to be just outside one of room corners in front of me.  
From there you can adjust continuous phase (a required feature), polarity (a required feature), crossover and level to phase and time align with your main speakers.  The result is seamless, non-directional perfect subwoofer integration and optimized power response.  
Bass actually is omni directional to the degree that low frequencies sort of crawl along surfaces and react to room corners, etc. If you walk around the room as Dudley suggests you understand this fact, not negate it. I have one sub right behind my left speaker, and another smaller sub a couple of feet away from my right speaker against a wall where I can easily put it in the window to service my deck sound needs when appropriate. The second sub sort of tempers the other one to smooth out the whole thing ("swarm" sub systems do that well I've heard). I actually would try Dudley's method if REL decided to offer their "Longbow" wireless system in a version that could be used with older models…I mean it's simply transmitting to something in the High Level input at the sub…come on REL! This aside, my 2 subs sound great as is.
Frustrated by sub positioning I once placed my sub at the listening position then walked around the room. The place that seemed to have the right balance while listening is where I placed the sub. Though there was some tweaking it worked really well in my blasphemous attempt to integrate a sub with my Maggie’s. ( closed rectangular room)
That's not Art Dudley, it's Steven Guttenberg. Get your audio nerds right, guys ;-)

(I doubt Dudley has ever employed a sub in his set ups).

The key is to realize that a phase knob can only add delay.

The real magic to sub integration is being able to delay the main speakers so that you can have the sub where it truly performs the best in the room without compromise.

Also, crossing over a pair of subs to your mains, regardless of how “full range,” will almost always be best.

Oh, and the realization that bass trapping (when done right) is crucial.  Completely different than room correction.
Oh Lordy, my bad. It is indeed Steve Guttenberg and not Mr. Dudley. A simple error rather than oncoming senility.
Yeah…Steve…this video does lack Art.
I had a real challenge integrating a pair of JL Audio F113V2 subs into my system, as the room had this "single note" it added to the music (regardless of what the bass player was playing), not a problem before I added the subs.
I found that moving the subs to a position in the center of the room, behind my sofa (and listening position) solved most of the "room issues", but the visceral listening experience was "off"...the tonality of the bass was not "directional", but the "feel" of the bass came from behind, while the music came from in front of my listening position.
Ten bass traps later, I positioned the pair of subs right next to the main speakers and once properly "tuned", all is "good".  The sound and feeling generated by my system is "consistent".

true, the phase adjustment does add delay but it has always worked for me.  my typical method is to reverse polarity on the sub and take an RTA measurement using uncorrelated pink noise.  It is easy to spot the main speaker's roll-off frequency.  Adjust the crossover on the sub to match, measure again.  There will probably be peaks or valleys near the crossover frequency.  Adjust the phase angle to flatten the response and then adjust the level by ear. 
Another important consideration is to avoid pre-amp connection to the sub and always use speaker level connections.  Much better for the sub to see the amplified signal that is identical to the signal the main speakers see. 
I use this method and have a completely smooth response curve with one sub from 20Hz through the midbass region.  It is non directional and bass comes directly from center stage- no peaks in the sound and as you said absolutely no room correction or EQ.  It sounds perfect.      
Best bass sound is when you sit on the subwoofer in your listening position. You really "feel " the bass...
contuzzi, erj1953,

I am using (2) JL Audio F-113 subs slightly behind and the side of  the main speakers. 
First I set them with there own JL calibration mic. 
Then, I own a DEQX Premate along with its many features it has an electronic crossover. With its calibration process you can set levels including delay. All of this frees the sub for placement most anywhere in the room.
I also have ASC Bass Traps in the corners of the room. 

@avanti1960  +1! about always connecting subs from the main speaker amplifier.  As you said, it integrates so much better with the main speakers.  I cannot tell where the mains leave off and the subs pick up with the bass!
I've had just the opposite experience connecting my JL subs to the speaker connection (high level inputs).  It changed the tonality of my system and seemed to soften dynamics. 

Using the outs from my pre-amp has been better.  I'm now going to try actually crossing over to my mains to check that out.

I tried one subwoofer, but I always had the impression, real or not, that I wasn't getting true stereo.  So I added another.  Both were positioned below or next to the main speakers because I wanted the wave front to be as coherent as possible - which doesn't happen when the mains and the subs aren't in the same areas.  Anyway, I continued to use the subs when I got my Martin Logan ESLs until one day when I disconnected them and found the sound much improved.  The subs (actually sub, since on was blown by a recent power outage) are now working with a pair of Celestion SL6si's.
I’ve found Mapleshades advice to be spot on.  2 are better than 1.  Subs should be within 1-2 inches of the mains midrange drivers and either interior or exterior to the main speakers.  Subs should face along the width of the room (180 degrees) to mains.  Speakers should face the long wall with the listening position against the back of the long wall.  Speaker position should be as nearfield and separated as supports solid imaging and accurate bass response.