The Descent II CD has its data on the first track, followed by 15 CD audio soundtrack files.  These CD audio tracks are not required for the game to work; they have been compressed here to MP3 format in order to save space.

These MP3's can be loaded directly into iTunes and used with D2X-Rebirth's Jukebox option.

Track List:
02 Title.mp3(Main Menu)
03 Crawl.mp3(Credits)
04 Glut.mp3
05 Gunner Down.mp3
06 Cold Reality.mp3
07 Ratzez.mp3
08 Crush.mp3
09 Untitled.mp3
10 Haunted (Instrumental).mp3
11 Are You Descent_.mp3
12 Techno Industry.mp3
13 Robot Jungle.mp3
14 Untitled.mp3
15 Untitled.mp3
16 Untitled.mp3

Descent 2 also reuses some of Descent 1's soundtracks for some non-level music (of which were not included in this package in order to keep download sizes small). If you already have Descent 1 installed/tracks loaded into iTunes then you do not need to worry about this. Otherwise you'll need the following tracks:

03 Outerlimits.mp3(Briefing)
04 Close Call.mp3(Escape Sequence)
14 Insanity.mp3(Ending)

This package also contains a new playlist file (descent2.m3u) for D2X-Rebirth as the builtin one DOES NOT work with iTunes 9 or later due to a change in folder structure introduced with it (if you have iTunes 8.2.1 or earlier, you don't need this new playlist file and can ignore the rest of this document as it's irrelevant). There are two ways to use this file. First, you can manually replace the original playlist file inside the D2X-Rebirth app bundle by right-clicking on the D2X-Rebirth app and selecting "Show Package Contents" then navigating to it's internal Resource folder and dropping in the new file replacing the old one. The second way is you can select the new file within the game while it's running by changing it within the "Jukebox Options: Path For Level Music" under the "Sound Effects & Music" category.
Also note that due to the same iTunes issue, you must manually select each of the non-level music tracks (02, 03 & reused D1 music) in the same "Sound Effects & Music" section. The track list above can be used as a reference for determining which non-level music is for what purpose.