Seems to me that one would be better served by spreading additional subs around your space, rather than making a stack. Adding more subs in the same spot does nothing to provide additional mitigation of any peaks and valleys in the rooms low frequency quality.
Stacking subwoofers
Dear,
I have a REL Carbon Special. Due to my room, it’s behind me in a corner with my speakers in front of me. I have the opportunity to buy two extra REL Carbon Special. I’ve been looking into line array… but I can’t place a stereo pair (the so called sixpack). Is it even worth the hassle to for from 1 to a stack of 3? Or should I focus on a REL 31/32 instead?
thx