You could also go the route of directly downloading from spotify with Zotify.
If you got premium it downloads in full 320kps. (Make sure to use the --download-real-time=True
toggle to raise no suspicion for spotify servers. This way you download as fast as if you were listening to the songs/audiobooks yourself.
Its a command line tool. Though if it can remove possible DRM Watermarks from the audiostream - no clue. But i wouldnt think they actually do that.
Happy, that you found my comment :D
I’ve also searched for such a solution for a longggg time. When i finally found it though… holy moly i was happy about that