> I think I'll hold off
> installing Airtime for now, until I get a machine I can use purposely
> for it.
It's not really necessary to wait, the changes to the system are all
reversible. I'm running Airtime on my desktop machine right now, see the
attached screenshot.
> By the way, would the inbuilt sound cards that come with desktops these
> days work? Or would it be better if I get an additional sound card to
> mount on the machine?
One normal soundcard is fine, as long as it has an ALSA driver (which is
standard in the Linux kernel). Pretty much all normal soundcards work
out of the box.
One limitation of doing everything on a single machine with one
soundcard is that the main output will be mixed with your stream monitor
output, and you'll hear a delay between the two outputs because of the
stream buffer. A work-around is to use an external USB audio interface
for the monitoring, directing the output of your media player to that.
It may be simpler just to monitor the stream from a second PC, if you
have one. That doesn't have to be a fast machine, anything with a media
player and a network connection will do.