Which wire has biggest impact?/

Digital coaxial cables are SO different from one another that I can make my system sound VERY different by using any of the three that I own. Each has its own virtues and shortcomings.

Which wire has biggest impact?/

a broken/ripped wire...will not transmit signals...
make sure yours are continued

The Poynting vectors don’t travel in the wire, silly. By the way, your auto spell check appears to have blown itself up. 

@bopper
off topic but I know a guy that goes by the nickname bopper.  Do you happen to play trumpet?  Does the name Crossmen mean something to you? 

If not, pardon the interruption.
if so, we know each other.

cheers,
Bruce

Millercarbon got it right - whichever one is the worst. 

If they're all the same, I'd start with the interconnect between the source and the preamp, then the preamp to poweramp, then speaker cable.