Are manufacturer AC cables good enough?

Ayre don't want you to have junk laying around  So they
sell what you want only  

Yes power cords can make a noticable difference.  I have heard it many times over and it is not placebo because I have heard expensive cables which I did not like.   The placebo argument is weak at best.  Measurement in audio are insufficient to really explain what is happening.  We can not measure everything we can hear.

+1 tjarmstrong

"Is he some sort of expert on all things concerning hi-fidelity?"

He is some sort of expert in everything. His credentials are on display throughout these threads.

If you are in a money-saving DIY mood:

Install an external LIVE solid AWG 16 to 12 copper or silver wire to a conventional power cord. 

Strip two inches of the outer insulation sleeve just before the connectors at both ends.  Then cut the LIVE wire (use meter to find live wire) leaving two inch tails leading to the connector at each end to which you can solder an external wire that is least five inches longer than the power cable.   Wrap live wire connections only with electrical tape.

Keep the external wire at least two to three inches away from the power cable's neutral/ground wires for the entire length of the cable and plug it in. 

Connect one of these cables to components one at time.  Audition the improvement as each component's new external LIVE wire cable is installed.

You can also start from scratch with connectors and wire. I use 12 AWG stranded copper wire for neutral and ground wires. I use solid naked silver 16 AWG wire encased in an 11 AWG Teflon tube or two layers of expandable poly sleeve for for LIVE wire connected to Sonarquest connectors. Frankly, the modified conventional cable sound about the same.

The theory is that parallel LIVE and neutral wires cause induction that produces noise.  Whether that is what happens is beyond my ken.  Whatever it is, it works.  Bass is tightened and voices are sweeter.

Compare results.

Cheers