power cables where do I start?

Digital can often make the biggest difference .
it is your main source all signals start there .you can enhance or mask the signal depending all on cables. And as I have been doing a lot of experimenting with power supplies in digital ,external 
a simple switch mode supply ,not good ,to a very elaborate Linear 
power supply that have regulators,chokes and 4 pole capacitors 
like from a Mojo Audio. We are talking up to a 20% increase in fidelity. I was given a challenge from Verastarr Audio ,usethere Copper foil awg9 power cord if it does not make a substantial improvement in fidelity within 30 days ,send back for a full refund .
he stated do Digital first . Then preamp . I took the challenge 
I now have 2. High quality is not cheap but as good or better then a component upgrade.

@sbrownnw 
Similar story here.
 Bought Signal cable digital, and a magic power. Like the digital on the source, and did not like the magic on my SS amp at all.
It just sits in a closet. Never thought that it might work well in a different location. Will give it a try someday in something else.
Thanks.

   LP

BTW, I've had good luck with Triode Wire Labs for the rest of my system. Good value especially used.

  LP

Signal Cable is a good affordable place to start. If you can find an Audience powerChord used at a good price, it's my go-to cord. It's not the best cord for every situation (no one cord is) and the degree of improvement varies, but it's extremely consistent. At its best (especially power amps) it can be transformational.