Tubes: As I wrote above, they involve 0% to audible changes. Some tubes hum at first, so yes, they can change.
Dynamic driver headphones and headphone pads can change. Some attribute this to the physical break down of the pad and the increased flexibility of the driver supports or surrounds. As a kid I and others put fingers through brittle old paper cone drivers, a sign of obvious decay.
Cables: The conductive material (e.g., copper vs. silver) is often obvious. However, some vendor claims are suspect. I therefore put cables in the “Other stuff???” bucket above. They are prime candidates for double blind tests as the impact ranges from nil to audible. It’s very, very hard for people to execute blind ABX tests because the ears, brain, and nerves take a while to habituate, and people experience fatigue over time. Many of us indeed fail rapid blind swaps. Again, I developed my fatigue evaluation playlist method because you can’t fake pain, tinnitus, and hissing in the ears. Pain might arise in seconds or over several hours per the setup (or never), but it’s the most reliable method I’ve tried.
Sources: Depends on the implementation. Again, check with multiple methods including electrical measurements and blind testing. Some people get goosebumps watching a vinyl record spin around…they love analog but may fail a blind test. Long USB cables do generate many errors in my experience, so no, digital is not just 1s and 0s. Other processing factors, such as Tidal’s high range filtering (not MQA), can be quite audible too.