If you listen to RFI with the podcast, you get an MP3 file. This file format is now very widely used for sound compression. How does it work?
In this podcast about mp3 you say MP3 is good for listening to pop music while jogging but not good enough for listening to classical music in a quiet room.
In fact, MP3 offers a trade off between bitrate or file size and quality. You can compress the same audio a different bitrates obtaining different quality mp3 files.
Doing double blind audio tests you can find the bitrate that makes the mp3 compressed file you are testing indistinguishable from the original.
For most music in ideal listening conditions that bitrate is between 175 and 245 kbps, that is betweeen 1/8th and 1/6th of an audio CD. The MP3 standard can go up to 320 kbps (1/4th) which is considered overkill.
If you stick to 1/11th then you are using 128 kbps which is in some cases not good enough in ideal listening conditions.
But other newer audio formats, like AAC, Vorbis and even MP3PRO, can achieve transparency at lower bitrates. For exmaple a Vorbis compressed audio is indistinguishable from the original in ideal listening conditions between 160 and 192 kbps.