Check the fronts LCR over again independently, first check (left and right) and lastly followed by adding the centre channel. Now you should be looking for a equal level on the (left and right) channels if you’re suspicious that one of them is wired out of phase reverse one of the leads to the fronts if the level goes up on the SPL db metre its in phase.
Now try the centre channel with left and right turned on and while playing wideband pink noise you should see an increase in the level when adding the centre channel, if you don’t see this reverse the lead for the centre channel if the level goes up its in phase.
Next play the LFE.1, but make sure you set the level to match one of the front channels, lets use the centre shall we, turn off the left and right and if you can see the level going up on the SPL db meter its in phase if the level is the same is out of phase, I’d say you’d solve this before the weekend.
A good Behringer DCX2496 with dedicated matching amplifiers driving the large Klipsch in active crossover mode might add more punch as well as the good features of its own crossover filters to address these common problems. Buy a few DCX2496 one for the fronts LCR and one for the sub and surrounds, and third to do the rest of the surrounds, you can’t make too many mistakes with this.
What else can I throw in you’re direction? “Arachnophobia” now that sounded awesome in THX during the title opening, the deep depth in (Trevor Jones) score was octave to octave of chest pounding tummy rumbling and in you’re face bass which is mostly produced from the centre channel on those large JBL 4675-A loudspeakers that is how its meant to be, now if you can get that happening without the mid high and high range being too unsafe in the dbA range of 85dbA with solid dbC going up to 105dbC to about 110dbC without stain, I’d say you it the jackpot almost!
The magic requires THX baffle wall to prevent the sound waves travelling back behind the loudspeakers, thus reinforcing the bass and projecting it out into the room.
