Do power supply units/cables make a difference in sound quality?

Those that claim to hear a "sound" from different power cords are in the throes of confirmation bias. Naturally the shiny new toy always provides more enjoyment - until the thrill wears off!

Ever since Noel Lee brought forth his Monster Cable company around 1976 the audio scene has been plagued by hyperbolic ad copy extolling the virtues and superiority of Cable A over Cable B. Before that audiophiles used zip cord and Radio Shack gray Switchcraft interconnects - and nobody complained! Suddenly manufacturers saw great profits to be made selling "audiophile grade" wire to the masses. All the claims of the superiority  of one cable over another have ZERO bases in scientific evidence. "My golden ears tell me it is so" is the common refrain! Like the eyes being fooled by optical illusions human ears and hearing are easily fooled!

I always protect my expensive equipment. I use maintainers with circuit breakers and of course surge suppression. The quality of the AC source is as important as cleaning the dust off a stylus.

Power cables and quality cabling are as important as quality equipment.

A few of my buddies use Threshold and I use to. You better use a good PC. It has nothing to do with looks is does have everything to do with performance.

No it doesn’t cost a fortune for very high quality cabling. I can purchase an entire set of cables for 500.00. I can make them for about 300.00.

Enjoy your upgrade and enjoy the new sound. Be patient, it pays. Be kind to your cables. Handle cables with great care and protect the terminal ends against static discharge after they are conditioned.. Everything matters..

+1 @helmholtzsoul 

A system's sound starts with the power supply of the various components. NOT with the wire from the AC outlets! RF noise from the AC outlets is a non-issue for any competently designed power supply.

A system's sound starts with the power supply at the point of origin, the service panel. A dedicated AC line is the best way to insure that appliances and electrical devices in the home are on separate circuits and don't add noise to the audio system. A quality receptacle and power cord should be considered part of the audio system. The use of a power conditioner is usually a benefit, but each owner can make this decision. I use balanced power conditioning with surge protection and the improvement in SQ can easily be heard. The power supply on components plays an important part by regulating voltage but can only do so much. RFI/EMI filters will further lower the noise-floor.

Those who say they don't hear a difference between a treated AC line (as stated above) may not have a system that is revealing enough to appreciate the benefits.

I don't think the quality of the electricity is as important as the quantity.  The PSU in your amp promptly rectifies it and regulates it so the electricity coming out of the wall it pretty much adequate in quality.  60Hz and approximately 120V.  A little noise that gets cleaned up almost totally by the PSU.

The quantity is more important.  You need a ready supply of quick current for your amp to deal with spikes or quick demands. This is required to make your amp quick and responsive, especially in the bass area.  

I think people often focus too much on quality and too little on quantity.  A generic 10awg cable will get you 99% of the way there by ensuring there is a ready supply of current.  Cleaning up the quality of the electricity may get you 1% since some tiny percentage of the "noise" in your electrical line may get through the PSU. But this is very tiny. 

Power strips and conditioners that limit current can do more harm than good.

Jerry