Does AC Power Cord to Linear Power Supply matter?

Linear Power Supply is a noisy switcher that operates at 120Hz. Current from mains is drawn in narrow spikes of high amplitude. Cable should have enough frequency response to handle it and to shield it from radiating out.

"Linear Power Supply is a noisy switcher that operates at 120Hz." This is key.

The PC is a 2 way street, allowing noise from the power supply to flow back into the mains and corrupt your AC to other components in your system in a very negative way. You won't hear the noise, but it will degrade SQ in subtle ways. Inserting a Shunyata Alpha Digital PC to the power supply of my Lumin made a huge difference. It is specifically designed to address this issue. AC borne noise is grossly misunderstood and underestimated by the average audiophile. Successful measures to eliminate it can result in stunning improvements in a system, equal or greater than a major component upgrade!

I should add to my previous comment, that hearing the negative effects on SQ of noise on your AC line (most often generated in your own house or by your own audio gear) is only likely if your system is already capable of high resolution. Owners of lesser systems may not notice a difference.

In addition to high frequency noise produced by LPS there is 120Hz component very difficult to filter out. In addition LPS in amplifiers is almost always unregulated (line and load). Recently quiet switchers operating at much higher frequencies appeared. Rowland used them in Capri preamp (no other reason than noise reduction) and recent top of the line class AB amplifiers (operating at 1MHz). My Benchmark DAC1 has linear power supply inside but the newest version DAC2 has internal switcher to reduce noise by another 10dB. Modern switchers operate/switch at zero voltage/zero current while LPS switches when voltage is the highest. Rectifier diodes are most of the time too slow to react conducting for a moment in opposite direction causing voltage spikes.

Of course not.