| Format | Quality | File size (MB) |
|---|---|---|
| plain old WAV | 36.1 | |
| FLAC | 0 | 27.9 |
| FLAC | 8 | 27.9 |
| FLAC | 4 | 24.8 |
| Ogg Vorbis | 10 | 10.7 |
| Ogg Vorbis | 5 | 4 |
| Ogg Vorbis | 0 | 1.7 |
| Ogg Vorbis | -1 | 1.2 |
| MPEG 3 | insane | 8.2 |
| MPEG 3 | standard | 3.6 |
| MPEG 3 | medium | 3.2 |
Personally I can't tell a difference between all of the above without listening to two very carefully. Plus, MP3 has patent issues. So I suggest that you use Ogg Vorbis with "-1" quality.
There's a great Bash script for converting wav, ogg, mp3, mpc, flac, ape or wma files into wav, ogg, mp3, mpc, flac or ape files here. I made a Konqueror service menu for this script that can be found here. Just put the audio-convert script somewhere in $PATH and audio-convert.desktop in ~/.kde/share/apps/konqueror/servicemenus or /usr/share/apps/konqueror/servicemenus and you'll be able to convert audio files by running (from Bash) audio-convert FILE or finding it in Konqueror, right clicking on it and going to Actions>Convert to another format.