Best place to install power cable

My first choice would be the Power amp, simply because it draws more current than any other electronics and a well constructed Power cable will better handle that current than a stock grade cable. Now, if you have a power conditioner, I would connect the power cable from your outlet to the power conditioner and plug your amp into the conditioner. You also should consider that a power cable composed solely of copper will have different sonic qualities than those composed with silver. On my transport, power cables composed of silver tended to produce very bright sonics. I think Gunbei has offered up some solid advice.

digital......

The bets cord always goes on my source (CDP).

I would try it on all your components and decide where it works the best. If you don't hear a significant improvement somewhere, you don't need it.

In my situation, using all Lessloss power cables, my preamp/dac provided a better place to put the pc, than the APL Denon 3910 that I use as a transport. But it wasn't until I added two pc's to my Nuforce 8.5's(version 1), that a synergy occurred.