Best digital cable below $500

I currently use a harmonic tech platium digital interconnect and am wondering if a better interconnect would make a difference. My system consists of a Theta basic II transport feeding a camelot uther IV going directly into a pass labs alpeh 5 amp to AP Virgo II speakers. Anolog interconnects are Tara labs air 1 and speaker cable is tara labs air2. Thanks in advance for your input.