After a lot of trial'n'error, I made an astonishing discovery:
My image format was CCD/IMG/SUB.
After removing the .SUB file, the audio works fine!
The background music now always plays!
The dedicated music player still fails, but that's irrelevant to the gaming experience!
Very satisfying now!
In the game Dino Crisis I also had some audio stuttering/skipping errors within the voice dialogues.
After moving the SUB file away, the trouble was resolved!!!
This knowledge is worth to be documented! As I don't want to spread wrong information, and could only speculate whether this really is a cause&effect, I kindly ask the experts to share their knowledge with us here and then add the respective authorized info to: