The less things between the speakers the better. I also run my subs behind my Oticas.
Yes it’s true, especially with these speakers. I now have the subs 3.5 feet from the front wall, behind the speakers, though not directly behind them. Almost against the side walls. This so far gives more, plenty of punch and believable soundstage compared to being in line or right beside the speakers. I don’t think I’ll do much measuring for a while at least, may tinker by ear the settings some more.
Measuring gets on my nerves too much, and honestly believe you still need to move the subs and listen anyway. If I had a better understanding of the measurements, maybe it would be more helpful. It basically just showed me the room mode in the sub range which wasn’t hard to fix.
Also I don’t like a flat response, I prefer a lift in the bass response.