Sadly I do not seem to notice the fade out it might just be because of the track I am playing, and it is checked.
What I am doing is adding on to EDDI series of commands that look at the music triggers in Elite.
So far have been able to get it to stop my current music on Spotify, and start playing Mass Effects galaxy map music when I go to the galaxy map in Elite, and then when you exit the galaxy map, it will stop that track and resume playing of the music on Spotify, but its cutoff is abrupt.