Placement of subwoofers

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

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.  

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.

Try the AM Acoustics room mode simulator

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