Where do cables upgrades have the most impact?

Factors that tend to increase the criticality of speaker cables:

-- Low speaker impedance.
-- Long cable length.

Factors that tend to increase the criticality of line-level analog interconnect cables:

-- High output impedance of the component driving the cable.
-- Use of unbalanced interconnections.
-- Long cable length.

Factors that tend to increase the criticality of power cords:

-- The component being powered has an unregulated power supply and draws large amounts of current that fluctuate widely. Namely most power amplifiers and integrated amplifiers.
-- The component being powered tends to generate significant amounts of electrical noise, that may couple via the power cord to other components. Namely power amplifiers, integrated amplifiers, and digital sources.
-- AC line voltage at the particular location that is lower than nominal. ("Nominal" being 120 volts in the USA).

Phono cables and digital interconnect cables involve complex issues that I won’t address in this post, but their criticality will vary widely depending on the specific equipment that is involved.

Regards,
-- Al
 

the sound of your system is the sum total of all the pieces.

As a newbie with very nice cables (but with OEM power cables) there is something I do not understand about power cables. Why does a manufacturer make and sell multi-thousand dollar amps with exotic power supplies but with power cables that are sub par. I just have a hard time getting past that idea.

I've got a Proceed HPA2 amp and when I read about all that goes into its power supply like two transformers (1 per channel) and know what these sold for new I have a hard time understanding why they would send it to you with a power cable that some here suggest would be de facto inferior.

I'm not suggesting that the right power cables can't make a huge difference, but if they can, why don't they come with the unit?

Why does a manufacturer make and sell multi-thousand dollar amps with exotic power supplies but with power cables that are sub par. I just have a hard time getting past that idea.

Ponder why component manufacturers showcase their products in partnership with any number of aftermarket cable companies?

BTW, you are way past the proverbial 'newbie' status. : )