I'll echo the sentiments of many of the above posters - but will add...
- yes - a good power cable on the power filter is a must
- a heavier gauge may or may not yield better results
- an advanced cable architecture, like the Shunyata Venom will probably yield better results.
I have tried many different cable geometries over the last couple of years and the top performers have been ...
- Braided Geometries, such as used by Anti Cables, which are pretty good from what I have read here
- Spiral Geometries, which the Shunyata Venom appears to be, which might provide the best overall performance.
I will add that I have not tried the cables mentioned above, simply because I build my own cables from scratch, but I have experimented with those very same geometries.
Gauge should only a factor if you have
- many source components plugged into the filter, or
- the power cable is used for high current draw amps
My system uses a NAIM 5i 50 watt amp and for that 12AWG is ample, but for 100watts or higher 10 awg and even 7 awg for 250 watts might need to be considered
As proof of the effectiveness of the more advanced geometries - a friend brought one of his conventional power cables over, which I then rebuilt in a braided geometry. So, same conductors, same connectors - just a different way of positioning the individual conductors...
- The results were a noticeably quieter noise floor, improved dynamic performance and wider and more detailed image when used on the very same source component - his words, not mine.
Personally - I make my own PC's in the Spiral Design and have compared and prefer them to cables using silver/copper alloys costing as much as $1500 for a 5ft cable. (see my "System" link below for details)
As for the exotic materials - all of my power cables are copper - no fancy alloys or silver - just some very good quality copper from Furutech and DH Labs
Hope this helps