Placement of Dual Powered Subs with Tower Speakers

thanks, I currently have one in between the speakers, though closer to one side, the second hasn't arrived yet.  The one is crossed over at about 40hz...looking forward to this, thanks again

the first sub is ideally placed, second sub facing straight ahead, or possibly on the side ?

I've been using a single S/5 Sho for the past year, and it is carefully placed and sounds very good

I appreciate that Duke

Thanks to both...the only placement obstacle that comes to mind is there is a single available electric outlet though I think it’s in a good place. Thoughts on long power cords? Thanks again 

My REL has a forward firing active driver and down firing passive 

Thanks to all...second sub arrived today. After initial set up with one in between mains but closer to left, and the other outside of right speaker, and closer to side wall...after fiddling with settings it is sounding quite good..know it will take more time to get it just right, but it is already quite good...hopefully in a few days a friend will come and we will move the subs around some and work more on the settings...