Using a pair of Sennheiser 540's, I compared a 256kbit LAME encoding to a 64kbit mp3pro encoding of the Presto, Chorale movement of Beethoven's 9th, and I found that the 64kbit encoding:
- the violin section seems 'blurred' together
- the timpani, as well as the overall bass effect, lacks definition ('boomy')
- the solo vocals sounded close to the 256kbit recording
- the biggest problems are when many sections are playing at the same time. For example, when the choir sings, the orchestral sounds much worse than when just the orchestra is playing alone(but not so bad that you can't tell what instrument is playing)