I’m setting up my old laptop next to my desktop. Currently my desktop, running Windows 10, is connected to an old Creative X-Fi USB sound card that’s no longer supported. It has some wonky drivers, but has pretty clean and crisp sound output when all the enhancement effects are turned off. For now, I can keep using that as long as it works. The laptop is running Linux Mint 19.3, and has a regular stereo jack audio output.

The obvious solution is hooking up the audio output of the laptop to the line in of the PC. Unfortunately, this solution picks up an unusable amount of line noise.

A software solution then, PulseAudio has a Windows build which supposedly can be used as an audio server that the Linux laptop could connect to. Streaming the audio over the network is reasonable. However, the last build for Windows appears to be 7 years old, and way behind the Linux version, so I’m going to pass on that.

How else could I hook this up?

USB to USB. I could pass the audio directly digitally using some device which passes as a USB speaker on one end, and a USB line in on the other end. So far I haven’t found any existing. Fortunately, I may be able to build this with some off-the-shelf components, either USB-I²S-USB or USB-S/PDIF-USB. The second solution has the advantage of having known support for optical isolation, which definitely would avoid any weird business going on. So far, I can’t find any S/PDIF USB input, though, so it might not be feasible.

For the USB to I²S to USB route, the PCM2076 appears to be solving one side of the story. Not sure if there are any out-of-the-box I²S to USB line input solutions, but we could build this ourselves using an FT900 board as a last resort. With some luck, we can optically isolate the I²S signal as well. This seems to be possible at least using an IL715E.

This website with a modular DAC seems to pop up a lot in online search results, so I’ll keep that bookmarked here as a reference.

Another solution could be simply to find or build a sound card with multiple USB inputs, instead of passing the audio through to the PC first.

To be continued.