I have disc 2 mounted in Daemon tools. Music is overwhelmingly loud, it drowns everything else. The in-game slider doesnt work. What can I do? Patched to the latest grayface version.

The Sound slider controls music volume when using MP3 music (the Music slider is used when playing CD music tracks). You should be able to disable the NoCD and PlayMP3 settings in MM6.ini to have it play from the CD image as long as the image is in a format that preserves the music tracks (it shows up as a music CD in media players). If the CD image doesn't include the music you'd need to copy your CD again in a format that supports them.

You may also need to set the virtual drive to be CD-ROM 0 for CD music to play, but I don't have the retail version to test that myself (instructions here).

Failing that another option would be to change the volume in the MP3 files themselves with MP3Gain or the like.

I tried all possible combinations with noCD and playmp3... no result. The image is in audio CD format (plays in media player as such). CDROM is set for 0, I verified.

Music is still at max. I wonder if this has anything to do with my computer. I have intel-based PC (cheap Staples desktop based on Sandy Bridge or something) that doesn't have volume sliders for CD in soud settings.

EDIT: Ok, I just went ahead and ripped the audio to mp3 per grayface patch recommendations, and everything works ok now. Thank you.