if by power we are talking mains then there is nothing that you can do to it that will affect the quality of sound.
uhh the transformer has a bode plot, the rectifier does some stuff to RF, then you have some filter caps and then a linear regulator. All those things have different zones of attenuations at frequencies due to their nature and the regulator has a PSRR thats based on DC voltage.
If you put something on mains you can filter out RF frequencies or even low harmonics of mains or you can stabilize the AC level into the unregulated DC supply which will lower the variation of voltage in the regulator so its PSRR will stabilize it even more.
if you look at some app notes they defiantly do specify beastly isolation transformers to act as filters before lab supplies that are further connected to ultra high PSRR regulators.
I never saw something metrological specify a CVT for any reason but it could theoretically work if your power is ultra bad. Audio equipment does not come with a spec and someone could have made something on very clean power that barely works and when you put it in a farm house it will not work well. Like if someone decided to run a power rail off a zener connected directly to the capacitor after a rectifier for the sake of elegance and simplicy or lack of know how and did not use a real regulator.
Or if you do something weird like run it with out the mains transformer because you have a high impedance 48V AC line on hand (filters here, not a cvt), but weird situations come up. Like running to remote lighting some where on a property. The circuit would not expect 400 feet of wire after the external transformer which used to be directly connected to the rectifier inside the chassis.