@mkgus
Maybe if we are talking $100 power amps or $30 DACs. Any issue with power supply would show up in measurements done by various sites (again, unless you live literally next to a radio tower, as the reviewers likely don’t), and it’s very rare for any products, regardless of price, to show any mains leakage (harmonic distortion every 60Hz, or 50Hz for Europe and whatnot).
Disregarding mains leakage and focusing on EMI, a 20¢ ferrite with most likely solve the issue.
Manufacturers have to build to certain price points
Maybe if we are talking $100 power amps or $30 DACs. Any issue with power supply would show up in measurements done by various sites (again, unless you live literally next to a radio tower, as the reviewers likely don’t), and it’s very rare for any products, regardless of price, to show any mains leakage (harmonic distortion every 60Hz, or 50Hz for Europe and whatnot).
Disregarding mains leakage and focusing on EMI, a 20¢ ferrite with most likely solve the issue.