Sorry, but mine is installed in the default GOG Games directory and it is experiencing the same issue as described above by Klesk22. I even attempted the "UseRedbookAudio=Yes" modification, which persists in userprofile.txt until the game runs and it is restored to its default value of "No". How can I get music to work again?
after changing the file you could try to set it to read-only, hence preventing CTP to change it (again).
As already suggested by JDKC in here: https://www.gog.com/forum/call_to_power_2/no_music_at_all_during_game/post9
Another thing: Do the people with those problems use this digital whatever it is called sound connection or a good old speaker/headphone?
redbookaudio normally refers to 16 bit, 44.1 kHz sampling, so you might want to check your sound settings IF they do allow it. I did see with other games that manually setting your sound option to those values does sometimes overcome this kind of problems.
Might also sound strange, but for those games it might be useful to have something like virtual clonedrive installed, just in case the program really wants to detect a CD as maybe your blueray or similar is not being detected and hence no sound being played.
Thank you for your help and assistance with this snarky bug. As for the first of the solutions you provided, I did already attempted changing the file attributes to "read only". As expected, the redbook audio flag does not change, but the game still has no in-game music. As for VirtualCloneDrive, I already have VirtualCloneDrive installed so that is not helping with anything. And finally, I tried changing my Surface Pro 4 to 16-bit, 44.1 KHz sampling (the default is 24-bit, 48 KHz) and the music still does not play. I am just using either the standard built-in speaker output or the headphone jack on my Surface; I am not using HDMI, DisplayPort or S/PDIF digital audio. I have many other old games from GOG (e.g. Starfleet Academy, Star Trek: 25th Anniversary, Caesar 3) and from my own library (Heroes of Might and Magic 3 with HD mod) and there are no such problems.