I was PM'ing this to someone and I decided to make it into a tutorial.
As anyone who has ever put a song into an animation will probably have noticed, when you export the animation to a .swf the sound quality drops a hell of a lot.
This is a quick explanation of how to get high sound quality in your animations.
In the following steps I'll be talking about a song, because that's probably the only time you'll really need this, but the same steps go for other sound files. As such I'm assuming you're working with a .mp3 file, and some steps may be irrelevant if you are using a .wav (like step 4)
1. Import the song into the library.
2. Right click on the song in the library, and choose 'Properties'.
3. If the check box that says 'Use imported MP3 quality' is checked, uncheck it.
4. Under 'Compression', choose 'MP3'
5. Under 'Bit rate' choose '64kbps'
6. Under 'Quality' choose 'best'
7. Uncheck 'Convert stereo to mono' and click 'OK'
8. Put the sound in to the animation by putting a keyframe and dragging the sound file onto the stage from the library.
9. Select the keyframe the sound is on, and go to the Properties panel (Ctrl+F3)
10. Under 'Sync:' choose 'Start'
Now export your animation, and the sound should be in crystal clear quality, as if you were playing it off a media player (iTunes, Winamp, WMP, etc).
Happy animating.
[EDIT]
I should also mention that this does raise the file size of your .swf like a mother ****er.
