Placement of subwoofers

I may be misunderstanding your response. 

[FYI Some manufactures offer Bluetooth or Wi-Fi connections as well as manufactures of decent quality custom length RCA or XLR cables available to bridge this new positioning.] 

You've placed one of your sub-bass speakers at the listening position and played a low frequency cadence of test tones through that sub and the main speakers while walking about the room? 

The priority is to map those areas where the bass energy is the loudest, ie. bass modes. It's not unusual for the next or lesser bass mode usually asymmetrical to the first. With the furniture out of the way map all the bass modes, everything else in the room is a null where low frequency is more difficult to achieve and control. 

With your sub-bass speakers positioned in the vicinity of these bass modes you'll be reducing the volume to your taste (shyness). You should hear an improvement in room loading and a more detailed low frequency presentation at the listening position using less gain. 

In my experience with your sub-bass speakers I found the addition of third party signal processing such as the DSPeaker to be very useful as have a majority of users making it a very questionable omission by manufactures.  

Despite the advantage of any signal processing, your sub-bass speakers remain a steep -6dB near the 30Hz region which usually limits extra low frequency output. Depending on your musical taste this may be a preferred non issue. 

All the best with your outcome. 

Appreciate the suggestions everyone. Very helpful! Below is the course of action that I am in the midst of carrying out based on the suggestions.

As I had removed most of my furniture from my living room to address this issue, I decided to get on my knees and do the subwoofer crawl (thanks @fstein ). I found the locations that I thought the bass sounded mildest (I am rather bass shy), and for now, have placed them on the right of the front wall (behind the speakers) and immediately behind my sitting position, against the back wall (thanks @avanti1960 ​​, @tablejockey , @12many ).  

Over the next couple of weeks, I will make minor adjustments to the location and gain of the subwoofers, in order to see what works best. Also, having done the subwoofer crawl, I now know the locations in my living room where the bass is most boomy and will try using bass traps to see what effect it has on the sound of my system (thanks @rick_n ). If all else fails, I will try the DSPeaker 8033 II as suggested by @kota1 .

Thanks everyone for the helpful suggestions!
 

Place a subwoofer on your seat and walk around the room. This will reveal nodes and optimum placement

IMO, you should try them at different locations and angles.  I have two subs and found the best sound (so far) by having one facing the same direction as the speaker and just to the outside of the speaker.  The other sub is at the outside of the other speaker but angled at about 60 degrees inward (toe in).  This removed the bloat in base that I was getting when them in the corners or facing forward for my listening positions.  Seems very room/furniture/equipment dependent.   It was a very noticeable change.  The big base sound is still there, but in the right amount.  

@dcpillai You have a very nice rig and have invested quite a few $$$.  This being the case, spending a little more on bass traps makes sense.  Adding the traps will do two key things.  It will give you much more flexibility in placing the subs.  Also, it will clean up the midrange of the mains.  Good luck and cheers.

@dcpillai : I am certainly nowhere near an expert in subs or their placement.  That being said, I have always found sound systems incorporating them, especially in a two-channel system, sound best when they are placed exactly between the left and right channnel speakers but not forward of those speakers.  A little behind them is OK, as long as the sub remains in the center between them and there are no obstructions in front of the sub. Kind of like why the drummer(s) in a band are usually always center stage and behind the other musicians, I guess. This would certainly complicate things in your room placement. You'd have to move your rack & components.

Subs in corners? LMAO!

I have two Rel T5/x paired with my Dynaudio Special 40 bookshelves.

My first experience with subwoofers, I initially followed Rel's guidance and put them in the corners of the front wall.

That produced lots of bass boom, prompting an all-day exercise, moving them all around my listening space (a living room like yours) to try to get upright bass transients clean and clear.

I ended up with them out in the room, on either side of the couch where I listen.

Strongly suggest (as others have) a room mode calculator like this one to try to understand where bass is piling up: Acoustic calculator: Room modes

That and a tape measure per Hans' room correction recommendations helped show me where to cut out certain bass frequencies below 300 hz with eq, in my case using Roon's eq feature. Roon eq is really useful because from your listening chair you can turn on and off the frequency band stops you assign based on your modes and room measurements and see how the sound changes.

Free basic room correction - YouTube

Can't say I've got a lot of boom now.

I also have the gain and crossover settings, that I set by ear, quite a bit lower than Rel's recommended starting point. This is likely due to my mostly square room, which I believe really accentuates the bass for me.

I'm no expert, just my experience. Happy listening.

I have responded to discussions about placement and performance of subs several times before this one. The room and surroundings are paramount in using them. They can add so much to the listening experience. Things get so complicated when it comes to which subs to buy and where to place them. Nobody can give you a definitive answer without visiting your environment..

I use subs and am pleased with the results. After looking for hints as to how to enhance performance I came across this article that is All About Subs. I know that the only best solution is to try things in your system is the best  but understanding how subs work may be helpful to you..

This article is long and technical at points but is very informative if you have the patience to read it. Good Luck in your quest......

http://www.soundoctor.com/whitepapers/subs.htm

Remember that subs typically have a 5ms delay compared to the mains and you need 1 foot for every ms to make up for it. I don't see where you can place your subs that far into the room.

All the best,
Nonoise

From my experience the best place for the subs is beside the mains. Mine were outside of the mains as I didn't have room inside. 

Can you describe what you may sense is lacking with your current sub bass speaker positioning?

Try the AM Acoustics room mode simulator

Looks like you have a solid choice of gear there.

Like many of us, you don't have a dedicated space, and limited to getting the most out of a living area-more importantly BOSS approval.

I'd try placing one behind the listening if possible.

Trust your ears.  

I have 2 RELs- both of which are behind the listening sofa. Very convincing and no unsightly additional boxes cluttering up the area.

"Based on the reading that I have done, I understand that the subwoofers should be placed alongside / parallel to the main speakers, and not behind them. "

 REL training  w/John Hunter I attended had them behind the speakers. The corner of the room was used as starting point and pulled out.  Also, the main speakers weren't necessarily equi distant in positioning.

Final positioning would look odd, but sound great. 

Speaker positioning was treated like focusing binoculars. No lasers, tape measure, DSP.

My 2 REL's are behind the listening sofa alongside the side walls.

subwoofers sound best where they sound the best, not necessarily even with your msin speaker.  

the general area you have them in could bo ok but i bet they need more distance from the wall to sound smoother, typically at least 12 to 20 inches.  

close to the wall often produces an annoying one note peak.  

i suggest an app and some pink noise to measure the response while seated at your listening spot.  you want to position them to reduce any narrow peaks.  

Well with 2 subs, I would place them in the corners on the front wall to reinforce the bass. This could cause bass boom, not sure if your subs can be eq'd to the room, but that would be helpful. That's why I prefer the JL Audio subs.

ozzy

The bulky furniture won’t matter as bass waves are omnidirectional. Place one in the front left corner (try facing into the room, then, try facing the wall about 2 inches away and see what you like better.)

If possible place the second in the back of the room, try both midwall and in the opposite corner and see what sounds better.

I am sure your wife won’t like bass traps so you can get a DSPeaker 8033 II to EQ them once they are placed. Check this out:

https://www.dspeaker.com/anti-mode-8033