Torben, if you’d browsed the forum a bit, you would have probably found out that there are subjective and objective camps regarding fringe audiophile cases and their audible merits.
So just read up on those and don’t start yet another thread that’ll turn into a waste of internet traffic…
If you use a LPS for a computer, on the computer’s motherboard there are all kind of voltage regulators as different components need a different voltage, and these are SMPS.
So, even if you are using a linear power supply to power the PC, at the end of the day, the components are still powered by internal SMPS.
No problem. Even with that, some people can hear differences, some do not. I personally haven’t ever heard a difference when used with a computer (or switch), but, if you can get one with a good return policy, you can try and listen for yourself.
Puh some strange and very generic „recommendations“ are made here.
I would recommend just starting with an ifi iPowerX 12V for your NAS (which has an easy return policy) which is about €100,- and you can easily see for yourself.