@pesky_wabbit,
I would take issue with your your statement. It is mainly cable induced (both mains and signal). if it is component induced the component is faulty or badly designed.
The most common sources of noise are cheap or poorly positioned transformers, and poor grounding schemes. Far less often is the noise cable induced. Cable noise is most often the result of a bad solder joint or complete lack of shielding -- rare, even with inexpensive cables.
I'd agree that noisy components are badly designed, but there's a lot of those out there. Cable noise in aviation and automotive is far more common than in home audio, but they're not apples to apples. I worked to mitigate noise in aviation systems for years, and more often than not, the culprits were poorly executed terminations or grounding schemes. In home audio, any halfway decent, inexpensive cable can thoroughly mitigate noise. Realistically, phono cables are the only ones that might require extra shielding and careful routing. The few times I've had cable noise in a home system were due to cold solder joints. In contrast, I've owned quite a few amps from various brands that had noisy transformers and/or bad ground schemes. It's quite common IME, so I take issue with your statement and assert that you sir are the one who is wrong. Silly Wabbit.