What speaker cable made a major difference in the sound quality of your speakers??

Exactly like @nutty. Same configuration for speaker cable and jumper wires. Changes were as follows:
The sound stage is much wider.
The bass is extended.
Highs were extended without being harsh.
Mid range is are much cleaner and life like.
Higher gain in the system, meaning the loudspeaker played louder at the same volume settings.

Downside - the "looks" of the Clear Day cables are not as good as the ones that were replaced.

@falconquest , you don't have to purchase the Clear days. Just talk to Paul at Clear Day. He will let you know which configuration will work better in your system. Then he will send you the cables, without taking your credit card information. Audition the cables, and if you don't like them, simply return them back to Paul. Good luck in your search.

@sunnyjim ,
For that much money, I suggest that you try the Clear Day Double Shotguns. I think you will be surprised by the way they make music.