it's not quite that simple unfortunately...the bands represent ranges of audio frequencies, not specific instruments. now generally speaking, bass tends to fall into the 80hz range, but it can go both lower and higher depending on the bass part. same deal with low synths, and really with all instruments.
it all depends on what kind of music you're playing, what kinds of instruments are used, etc
the 13hz band represents the highest frequencies on the spectrum, which could be voices, high pitched woodwinds and reed instruments (like flutes), high pitched stringed instruments, the upper range of a guitar, cymbal crashes, high pitched synths, things like that. raising it makes the overall volume seem a lot louder because of the way those frequencies hit your ears, but it doesn't actually affect the overall volume any more than raising the gain for any other band.
the new settings seem to rely heavily on the new reverb effect, which partially explains the "empty" feel. and yeah, they also seem to pull out a lot of mid range (although this is also a natural side effect of adding heavy reverb, so they might not actually affect the mid range at all - I kinda wish Cowon would let you get into their presets and at least look at them, if not edit them yourself).
Ok so about the EQ.
From my experience of messing with it, the 80hz band is pretty much the bass. The 220hz band is the low synthesizers, the 780hz is mid synthesizers/ treble, the 3.0hz is the high synthesizers/treble, but what is the 13hz band? When I mess with it, it seems to lower and raise the overall volume and "higher" sound. But I can't tell what it affects directly.. (voice maybe?)
The frequency I mainly just left alone.
My configuration is 10, 5, 3, 2, 8
BBE 1, M3B 1, 3D 1
And the new Settings Crystal Clear, Maestro etc.. seem to just emphasize some lows, treble, and high synthesizers. But the "empty" like feeling comes from the lack of mid/mid synthesizers?
I wish we could see what settings the presets were on..