For my radio show/podcast I'm recording my microphone and play music from a music player software. So far I've used audacity and it records both inputs into one track. This is hard for post-production when I want to edit my microphone input separately from the music. So, what would be ideal is to record the mic and the audio on two separate tracks. I already have two virtual sinks via PulseAudio for that and wonder if I can simply route them into ardour.
I have the feeling that ardour can only deal with hardware devices, so another option would be to output the virtual sink on a hardware device and plugin that back into a hardware input. However, this would lead to quality loss which would be unfortunate.
Edit: Found a solution with ffmpeg (see answer).