Are manufacturer AC cables good enough?

Ha ha ha!  The "religion of IEC cables" !!! You have the power cables that run in the walls from your power center to the AC outlet near your soundsystem:  They are just plain straight parallel copper cables @ cents per feet...

And you would get "a much better sound" placing those "magic IEC cables" between the AC Outlet and the equipment?   We call that the placebo effect and it will cost you a premium!!!

Not only that, equipment must be certified for EMI and the power supplies / casing must be designed for that.  And it's not like power supplies are new technology...  If your equipments are so "fragile" not to support a normal environment, it is simply by mean of a bad power supply design.  In that case, change that badly designed equipment for something better, whatever the price you paid...

@itsjustme Exactly!!!

My $2600 phono amp improved by a notable amount by replacing the power cord with a $39 OFC cable with rhodium-plated plugs. The manufacturer should supply a better cable than the standard dollar cable.

Clearly there are those who cannot hear, or do not care, for the improvement quality wire can deliver. These people can save a lot of money. They should be happy. Why then are they so crabby? Could it be because they cannot hear? And spent a lot of money on sound they do not care for? That would do it.