Big music related question

[TRUEpiiiicness]

As I'm going to swap music around in Descent: The Countdown to be appropriate for the level theme in Countdown mode, I'm adding five extra tracks to stop the repetition on levels 23-27.
This brings me to the question:
Can I use music from other missions such as the Lost Levels, Obsidian and The Enemy Within if they DON'T say I CANNOT use it.
Because let's be honest, D1game15 isn't gonna cut it.

[LightWolf]

Lost Levels is just taken from sites like vgmusic.com etc, so that should be OK. You should ask someone involved with Obsidian for permission there, and maybe ask Darkflamewolf for permission to use TEW music.

That said, sites like vgmusic.com do provide a pretty nice chunk of free-to-use-noncommercially music provided you don't mind it being midi remixes of already existing game music. If you need some help looking, I can help with that.
One thing to be careful of - I'm not sure if the limitation's been removed, but I've heard there is a 24-track limit in D2. If you don't mind replacing non-level tracks this is a viable way around the issue (menu, briefing, and credits are all that would need replaced; there may be other options as well if you want to preserve the menu track).

You should be able to fit D1L15 music into a watery early-game level fairly easy... (early game because you should generally have more time then thus leaving you more relaxed)

[TRUEpiiiicness]

I'm not sure if the limitation's been removed, but I've heard there is a 24-track limit in D2.

Ive heard this too so I looked at plutonian shores and I think I remember seeing more than 24. At that time though, I thought the briefing, credits etc didn't count towards the total.

You should be able to fit D1L15 music into a watery early-game level fairly easy... (early game because you should generally have more time then thus leaving you more relaxed)

Level 4 for that then because that's definitely going to a water level