I want to second this motion and extend it to say that the power supply can affect things in all sorts of devices in ways you would never imagine. In an earlier life, I was a bench tech, first at Lexcion (I’m talking WAY back), and, later, for an importer/distributor of European electronic instruments. I can’t tell you the bizarre problems that I eventually traced back to power supply problems. Really subtle stuff like missing menu commands, intermittent glitchy sounds, and on and on. Again, these were *digital* devices!
And, again, for power supplies in amps. I spent four years at Meyer Sound, and one thing John Meyer talked about was that some amplifier companies would cite the maximum voltage output of their amps in order to indicate their headroom and ability to respond to high-peak transients, but, he pointed out, they often could only *maintain* that output for a few milliseconds or even just some number of microseconds, where a transient could have a high level last for up to tens of milliseconds. Thus, such amps could reproduce the transient *level,* but not necessarily accurately reproduce the actual *transient* itself.