How important is the transport when using a DAC?

I would really welcome someone demonstrate this difference in sound for me. I have yet to hear it.
Many fairly high end CD players used to use 29 dollar computer transports.

Then again, they are selling Cardas Gold CAT5 cable now for music servers...so go figure...

Did I just read (again) that a power supply is better than a chemical battery to provide DC to a component?

This sounds like the Naim dealer who insisted two car batteries would not run a preamp. The 24 volts would not be "clean enough" and the performance would suffer.

Sorry to sound sarcastic...and I am not claiming to be the end all guru here, but a battery is perfect DC, is it not?
Especially for a preamp or DAC/CD player application which is essentially a stable load.

But isn't the variance caused by the dynamic nature of the power demand?

I get the transients and "current derivative" or what some in slang call "load backlash," but this is microscopic, no? ...and from what I know, the down-line component would almost have to be "designed" to place the onus on the supply, would it not?

This is the hairy edge of my knowledge and I intend to learn more about it. Answers to the above will help if you have the time.

Coming from a "battery is purity" background...this will be a learning experience.