I have the following problem.
I have a 5.1 surround sound system using a Sony AV receiver. This is connected to multiple devices for audio, including my PC. Since the PC is a little bit far away from the AV receiver and there are power cables along the way I decided to connect the PC with an optical cable (SPDIF) to the AV receiver. This works, but unfortunately the driver for the onboard sound card of my mainboard is not capable of using the digital output for surround sound. All I get is stereo. I don't want to use the analog jacks, as they would need to be at least 5m long and run right next to mains power cables. Using the analog jacks would also require 3 cables instead of just one.
So I am looking for a relatively cheap (<100€) sound card for the PC that can be used for at least 5.1 surround sound over optical. This needs to work with Windows 10 and Linux.
PS: Please only suggest things available in Europe.