adding second set of speakers

Too funny. Especially since, if that's what it really was, it could be eliminated quickly and for free as easily as reversing polarity on one or moving one or the other out of the corner a little one way or the other. 

well now mate, I did try moving the speakers around. I had them setup L and L + R and R maybe more like this evil sketch:

L       R

L me R

ok, based on this new information I called corporate and asked for a few quid to continue these R&D activities. Seems they have an endless bucket of money from a death ray started in the 80’s and its no problem to shuffle funding for really trivial stuff..
#1.. so I connected the JBL LSR 305’s arrayed exactly as previously but to the full range inputs... hmm, now that sounds better but I am still getting this weird feeling in me noggin, sorta like Bombay Sapphire gin tonics where you know you are gonna have a hangover but you are powerless to stop...

#2... still on the full range subwoofer inputs, i hooked the JBL L-R channels up out of phase along the common L-R boundry.. if ya can dig it 
L      R

R me L

in the end this was equally unsatisfying. Before I started this walk down the wylde side I would not have thought the LSR 305 sound quality would be detrimental to a swarm sub-woofer setup, but they most certainly are and detracted from the LSR 310 subwoofer. I guess the 310s is better than I thought...

thus endeth me trials of sonic grooviness