@squared80 this is not entirely true. First, often supplied power cables are poor quality. Cost cutting. Pass cables are pretty good actually, properly designed. Hospitals use medical grade connectors - so they care about better power connection, right?
There is indeed a LOT of snake oil. But there are also poorly designed power supplies…
Nelson has an excellent writing on how much Class A amp must weigh. And if weigh less, you are getting scammed. Because amo must have proper power transformers and headsinks and they weigh a lot.