It's got to be mp3
FLAC is a load of rubbish. Plays on hardly anything. A dead format despite so-called "audiophiles" raving about it. The files are way too big ( about 50% of the original PCM file ) If you look at the portability, download speeds and ease of use, which are the main issues, it's got to be mp3. . For the majority of music, 192k VBR ( Variable Bit Rate ) sounds pretty close to a CD. Well, for most people, I think even 128kb is good enough. They can't tell the difference.
Mastering nowadays squashes all of the dynamics out to make it as loud as possible, and actually ADDS digital distortion, anyway.
{ I just want to clarify to Aitor that (audio)"compression" used during mastering , is not the same as (digital) "compression" used to make an mp3.
Audio compression cuts the dynamics / digital compression discards ( to most people ) inaudible and therefore useless frequencies}
If you really want a true rendition, buy the CD and encode it yourself. Or just play the CD ! Most people just want to download a song into their iPod and have it available to play wherever they want with the least amount of hassle.
If you want to listen to lute concertos on your 8,000 quid electro static speakers, then mp3 is probably not the way forward for you. You should get an SACD player ( or a girlfriend :-) )
Oh, yeah ! ... and back to the main point : DRM is complete rubbish, as are most attempts to shackle music. It's just a pain in the arse for consumers ( see the Sony copy protect CDs debacle ), and less scrupulous people will always find a way to work around it.