There used to be software called Airfoil, that sent audio from one computer
to
any others. However it has been discontinued.

The spiritual successor seems to be this:
https://www.stardock.com/products/acousticbridge/
And before you ask: I don't know if it's accessible.

As for more DIY answers.

Doing this kind of thing was much more popular 10-15 years ago it seems.
Most of the solutions out there speak of Win 7, vista, or 98. Most software
for
doing it has gone away now, or can only be found in very old versions.

Pulseaudio can do this, but God bless you and help you if you decide to
spend
time working with Pulseaudio. Even I won't go near that one any more.

There are several possible solutions here:
https://sound.stackexchange.com/questions/22921/stream-windows-audio-over-the-network

The best one seems to be the Edcast -> Icecast answer, but even Edcast is
only
available in the Google Code Vault.

Another (partial) option might be this software here:
https://github.com/duncanthrax/scream

It claims to only work on the local network, but if you are clever with
networking and such you might be able to convince it to work over a point to

point VPN or something like that.

Were I to try this, I would probably use FFMpeg to pick up the local PCM
stream,
convert it to MP3 or OGG, pipe that into a local icecast server, and have
your
remote machine listen to that compressed stream.
Alternatively, you might be able to do something with VLC, but I'm no
expert.

There are recipes out there for going from Linux to Windows via FFMPeg and
FFPlay. I'm sure you could adapt those for Windows-to-Windows, using the
loopback sound driver that Windows has.

Good luck.

--
Luke

"In this life there are obstacles, and forces who overcome obstacles. You
can be either one or the other.
If you refuse to even try to clear an obstacle, you become the obstacle."
- Joel Shepherd