What are my options for streaming multiple low quality, mono, audio feeds over my home network, from one PC or cheapish non-PC hardware?

Ultimately 3 USB soundcards in one PC -> streaming software that can deal with all 3 -> software client elsewhere on LAN that can choose between the 3 different streams
Little magic box that doesn't require a PC that has 3 audio inputs (or 3 single channel boxes) -> software client elsewhere on LAN.

From what I have found the Windows software that is available uses the default windows recording device rather than giving you the option to choose your sound input device, so it's fine for one source (or at a push 1 source per left/right channel) but not so good for 3 or more.

I don't really want to mix the 3 sources before feeding them into the PC and stream them as a single channel.