I also think you should explore placement issues before investigating new electronics or cabling. However, I think you should look to make sure that you have eliminated or reduced your sidewall reflections. You would also want to play with toe in - many speakers are hot if listened to on or anywhere close to on axis. You can point them straight ahead or if you have problems with sidewall reflections you can try toe them in substantially crossing them well in front of the listening position. Give it a try - it cost zip.
