Is digital contamination that big of a deal?

Digital gear can generate a lot of RF noise that can have negative effects on other nearby gear. Its gotten much better in recent years but still something to be aware of. Really good sound is all about minimizing noise and distortion.

"That's why I'm wondering if I should run a "digital" PC to my digital gear or just a "regular" high quality PC?"

It can make a difference. Using reasonably affordable Pangea ac14se power cords for noise control made a large noticeable difference with both of my DACs in both systems. With my tube pre-amp as well but perhaps to a lesser degree.

"I've come to realize from firsthand evidence that Everybody's system is Absolutely CHOKED with all manner of electrical noise."

From my experience, I would say if you want the best possible sound our of your gear, noise issues associated with digital gear must be addressed on way or another.

IMHO, noise associated with digital gear is in most cases the secret reason why digital gets a bad rap with audiophiles, not the gear or format itself.

So best to consider it an issue and address both noise levels in the wiring and in the air.

Here are some things to cover:

1) keep physical space between components, and digital gear in particular

2) when in doubt use power cords and ICs that offer isolation/shielding from noise

3) If possible, plug analog source and amplicication components into a separate outlet from digital gear and from any other inherently noisy home items, things like flourescent lights, microwaves, computers and peripherals, etc. Separate circuits are even better if possible.

4) Do some resaerch on gear before buying to determine if users report any unusual noise issues with specific digital or switching gear like Class D amps. Newer design Class D amps tend to have better noise controls designed into them than the early models from just a few years back.

Yep, its a real issue in general so worth being educated about and alert to but lots of variables in play case by case so YMMV and it might in fact not be that big of a deal in most cases on the grand scale of things.

In my particular case, with multiple systems that play in multiple rooms, I find it always to be an issue to some extent but how much varies depending on exactly what I am listening to. The negative effects are typically greatest in cases where one is doing highly critical listening in good conditions with good gear that is well matched and performing well otherwise and a good recording to start with.