Don’t overlook variable bitrate (VBR) for mp3 files. It seems that they’re much less used than fixed bitrate mp3, and there’s even a bit of prejudice against them from engineers but that seems mostly theoretical. In any case I think they give the best quality/file size ratio. I use a LAME encoder where the best quality VBR mp3 come out averaging 220Kb/s – a bit higher than 160. If you wanted smaller files then go down the VBR scale a bit.
I think the main difference between mp3 and original CD is mainly the lack of depth in the sound even if plenty claim that higher rates are indistinguishable. Personally I don’t really like mp3 at all, the ogg vorbis format is a much better sound for the same file size, but mp3, the early starter, is ubiquitous so I stick with them too on my site.
My work for flute, viola and harp (Terrestrial Mirror) is using variable bitrate mp3 at the highest quality (220Kb/s), and was recorded professionally. The harpist was employed as a sound engineer for French TV, and she got a colleague to record us.
.
