noisy sound inside pcs

No they don't. I do exactly this with my sound card (Echo MIa), and
it
is of extremely high fidelity, and has never made even the slightest
pop or whistle. If you are getting extraneous noises, it is very
likely you are running your sound card on an inadvisedly shared
interrupt. It certainly isn't normal behaviour.

I've got a Shuttle XPC and was using the onboard sound. Since this
has a single PCI slot (which is already in use). Shuttle XPCs are
known for this as well and part of the problem is likely to be the
close proximity of everything inside them.

The sound card you've mentioned is almost certainly excellent but it
also cost nearly as much as my Shuttle and 2.5times the list price of
the USB sound card i've bought.

snip
It is the care taken to avoid contamination of audio outputs that makes a PC
quiet or noisy, sonically.
and this isn't something that is very often a priority for a PC and
thus not something the designers are likely to have focused on. In a
CD player the manufacturers have full control and can ensure that
internal interference doenst occur. With a PC the user can stick a
graphics card with a gert big fan on it immediately adjacent to the
sound card.


It is a false claim that putting common line-level audio circuitry inside or
outside the PC case necessarily makes an audible difference.

maybe not in terms of a 'breakout box' but keeping the audio digital
until it's outside the box (by putting it over USB) has been effective
in my case.