Though I have generally been pleased with vorbis as a codec, one problem area has continually stood out to me: the apparent magnification the treble range. So while files encoded in vorbis typically lose fidelity in a "graceful" manner - that is, I don't notice specific artifacts very often - they are very easy for me to distinguish from the original wav files when played back-to-back because of their magnification of upper-range treble. This difference is more noticeable on certain songs, of course. On the opening measures of Nirvana's "In Bloom", I am able to consistently distinguish the original wav files from ogg files until the 6.0 quality setting (average bitrate around 200 kbps). For a given file size (or average bitrate), RC3 sounds a touch better on this clip than does RC2, but it's not that great. I hope that this problem isn't related to the codec's framework, and think that this issue should be worked on. For the record, I'm testing with a relatively cheap set of speakers (typical small stereo tweeters and floor subwoofer unit) and low-level soundcard (SB Audio PCI Mixer).
You should submit a sample to monty, who is pretty good about fixing things.
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