which power cable and USB cable for my Innous Zenith Mk3?

I have the Zenith MKIII. It came to me with a Transparent USB cable which I replaced with a WireWorld Platinum, OCC silver. This was a significant upgrade. I also put a WW Silver Electra power cable on it, but I did not notice any significant improvement from that change.

My Innuos zenith mk3 uses a USB cable over $700. Connecting it directly to the dac was not the answer. Once I got a DDC, connected the USB to it and came out of it with I2s to dac, a veil was lifted. The sound clarity was so much better, it stunned me. 

Like @grunge1000 , I was skeptical of how power cables could affect the SQ of a system for the first 2 decades of  being an audiophile.  Everyone can hear the differences in components, and intercommects, and speaker cables.  I couldn't understand why power cords would make a difference.  I even tried switching out power cords, and I didn't hear any difference.  However, many people commented about the effect of power cords on SQ, so I tried upgraded power cords ($100-$300), and I heard no difference.  However, just last month I tried markedly upgraded power cords ($2000+), and I easily heard a significant difference when plugged into my pre-amplifier.  When I plugged these cords into my amplifier, the difference was not obvious.  Consequently, I now will have to agree with @kennymacc that power cords can make a difference in SQ, but not always for every component and not every power cord.  The most prominent improvement in SQ that I heard was when used into my pre-amplifier.  As for which power cords?  I would have to say that it's like interconnects:  trial and error is the only way to really konw!

I use a Stealth Tunable USB and a AQ Tornado source power cord 

snd sounds very good ,the New Stealth tunable is great you can literally add bass or lessen fine tune the detail. Anthony at Perrotta audio consultants  gives solid deals .

Grunge1000  what does your audio system consist  of ?

if you can’t  hear the difference  in quality. Power cords 

then it’s either the quality of your equipment ,ears or both. 
if it were not so 95+% of all Audiophiles wouldnot be doing it.