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

I think the OP wanted confirmation that he wouldn't hear a difference when adding power supply treatment.

His only interaction was with fellow non-believers. This thread was a waste of time.

+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.