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

As you can see, some say yes and some say no. The only way you can come to any conclusion is to try it yourself. Personally I found that some power conditioners can adversely effect SQ and that spending big bucks on power cable is a waste of money. There are many cables around $100 that will do the job admirably.

Indeed. That is my conclusion.  I will invest in a new cartridge for my turntable.  I think the Koetsu has worn down.  That will make a hearable difference playing records. Thanks all who took the time and trouble to answer my question.

@baumwoll For nearly 25+ years, I never felt the need to change power cords, fuses, interconnects, add power conditioners to "improve" the sound from my audio system. @jasonbourne52 pretty much summarized the technical reasons behind why such changes don't make a difference.

Electronic components have built-in power supplies that controls the DC voltage/current ultimately responsible for driving electronic components in the audio path. Some components have multiple power supplies with well regulated for fluctuations in the AC supply. This is not rocket science anymore, but well established design concepts of audio gear.  Adding power conditioners, changing power cords/fuses won't make an iota of a difference. Same goes with cables and interconnect where most commercially available at "reasonable prices" can get the job done. I have Kimber 8TC as speaker cables. All the components are plugged into surge protectors with power amp having its very own. So don't fall for marketing gimmicks and save your money

pwerahera I have the same view as you express in your post.  I wanted to see if anyone on this forum could give me convincing argument to change my mind.  The cost of these power control units and cables is far to high for the benefit the purport to deliver.  Good quality surge protectors and a stable source of AC is all I need on that end.

To a degree depends how revealing your system is.