Stock power cables for 15a use are standard 12 gauge. (for standard power cord lengths)
The three 16g cables used for each phase of the Valhalla form an aggregate of 11.3g.
Explain to me how 16g is larger than 12g.
The only time the power cord to the electronics will be smaller is if there is a wall wart (transformer) at the plug. In which case, it doesnt matter. Did you rewire a wall wart???
When I bought my used Krell power amp and P300 Power Plant from USA I got two stock cables that said 18awg on it.
When I bought new stuff from PS Audio I got a thicker cable in the box.
My apartment wiring is 14-16awg. Thicker than 14 awg removes detail in my system.
BTW. The Nordost Shiva is 18awg.