Position of speaker cables and irregular behavior

 I move my speakers around a lot, experiment with placement, also move a few different sets in/out of rotation.  Reason:  I have a persistent problem in that my left speaker is dominant. Playing in mono the image is centered about 2 feet left of center. In stereo, not only are vocals shifted left, the right side just doesn’t carry the same level of volume , soundstage and depth. 

Equipment: Bryston 7b monoblocks, Bryston pre, Opp BDP105, Grover Huffman Empress speaker cables, Siltech xlr interconnects.

I have swapped/reversed every single component to try isolating a culprit. No luck.

Although there are differences in left/right side walls in the room, the parts that matter ( reflection points ) are basically the same.

my speaker cables are 8ft so I have about 3-4 ft of excess. When I move the cables around it affects the dominance to either lessen or exaggerate to the left.  Sometimes I get close to almost centering the image , when that happens the right side blooms open. But it lasts a few hours or days and then I’m back to playing with speaker and cable placement.  I’ve suspended the cables off the floor , sometimes helps temporarily. 

I have tried adjusting the balance on the preamp . that makes the volume equal but not the brilliance of music which remains duller on the right.

There are even times when I’m listening to a song and as I’m listening the image shifts either more to left or more to center.  I thought it might be a sound pressure issue in my room, then I move the speaker cables and it gets better....for a while.

its not my hearing, when I attend audio exhibitions or meets the sound is equal.

I have moved my speaker cables so many times, like bending a wire hanger back and forth, they eventually broke. Grover huffman was kind enough to repair my speaker cables...twice.. Have some bending going on to fasten on binding posts. 

I sprayed Deoxit on all connections, that didn’t make a difference.

i routed all power cords neatly and away from speaker cables.

I’m thinking of getting 4ft speaker cables so that I have a straight run. Otherwise I’m out of ideas.

any help?