Should the better AC cable be used on Amp? Source?

Hi everyone,

Just curious about this one. Let's suppose that you have 2 AC cables, one being more upscale than the other.

Where would you use it? On the amp or cd player?

Please avoid the ''use the one that sound's best'' type of answers - I already did this and the results vary from recording to recording.

As a general rule of thumb, what would you say?

Thanks!