CBR va` VBR??

VBR "theoretically" offers the best quality. Theoretically, because this is only true, if the psymodel would be perfect. Most of the time, the psymodel works right, so quality is indeed better - but in rare cases, the encoder may encode a section with too low bitrate, because it underestimates the "difficulty" of that section.

In practice, CBR cannot compete with VBR at the same *average bitrate*. However, if you encode in CBR at the maximum bitrate - i.e. 320kbit.... then the encoder always assigns the maximum bitrate... thus, it can never happen, that the encoder assigns not enough bitrate. The downside off course is about 50% bigger filesize, since a similiar perceptual quality could be reached with VBR V2 at about 200kbit average.

What it comes down to is this: Do you want efficiency or perfection? If you want efficiency, then go with V2... you get sufficient quality at reasonable bitrates....... If you want perfection, then even CBR will not fix your paranoia, because there are ultra-rare artifacts, which cannot even be fixed at 320kbit, because they are the result of limitations of the MP3-format.... thus, you would need to switch to either lossless at around 700kbit, or a hybrid-lossless encoder in lossy-mode, like WavPack lossy at around 450kbit.

Another way to look at it is this:
VBR V2: 100% filesize, transparent to almost everyone more than 99,9% of the time during normal listening.
CBR320: 150% filesize, transparent to almost everyone more than 99,99% of the time during normal listening.
WavPack lossy @450kbit: 225% filesize, transparent to almost everyone more than 99,999% of the time during normal listening.
Lossless: 350% filesize, bitidentical so 100% transparent

If you look at those simplyfied stats, you will understand why VBR MP3 is so popular here: It is the most efficient choice.

Summary: MP3 was not designed to be perfect. It was designed to be "good enough" and to deliver that at very space-efficient bitrates. VBR delivers this goal the best. If you want perfection, then look elsewhere than MP3. This may sound harsh, but there is no other way to get it.... mp3 is not perfect, and it doesnt need to be perfect... its purpose is to be "good enough". People who want absolute safety and perfection should not use MP3, because it wasnt designed for such a purpose.