I noticed that at some point (or maybe it's always been there?) a playlist feature was added to the right-hand side cockpit console, so you can listen to the audio descriptions in the codex (the potted histories etc. of the different powers and so on). This got me wondering if you could add your own tracks to it but it seems that's not an option.
Whilst searching for an answer on this I discovered a couple of fan-made unofficial radio stations. They broadcast mostly music but also some in-game info, hints and tips too.
Radio Skvortsov - Covers a range of genres from the 60's to now, mostly in English but with the occasional foreign tune included. It even includes some tracks that I wasn't expecting to hear (Yes' Homeworld (The Ladder) to name one, and some random user-made tracks that can be found on YouTube).
Radio Sidewinder - Generally a range of electronic, ambient, new age and techno-type stuff. Mostly instrumental.
Just something different to listen to when you're long hauling or whatever.