Bryston 14BST and Polk SDA SRS Speaker Cable?

I'm currently running some thick Monster Cable (model number escapes me) speaker cable and would like to upgrade to a bi wire set up for this rig. I'm pushing a lot of power and like to listen to rock and blues music on the loud side. I'd like a cleaner (less muddy?) midrange (if this is possible with a cable adjustment). Top and bottom end are fine. Current research has me leaning to bi wire Kimber 8 TCs or an Alpha Core M1 bi wire. Used Cable.com recommended a new "Wireworld Atlantis III+ Internal Biwire" as the "perfect" match. However, I'm a tad skeptical, as this cable is the one currently on a special purchase on their sister company, "The Cable Company". Any suggestions in the $500 range?