Here are some of the built-in Ipod equalizer presets that represents a V-shaped equalization, mainly to reduce the midrange areas and boost the bass and treble. You can use this if you feel that the midrange is too thick, or want more bass and treble presence.
The Rock EQ is a classic V-shaped curve.
The Classical setting is like the Rock setting, but with more upper bass (higher 250Hz level).
The Jazz setting is another variation of the V-shape curve. It's interchangeable with the Classical and Rock, depending on recording and system matching.
The Acoustic setting is a milder variant of the V-shape curve. It works to make certain recordings more airy by lowering the midrange area and adding a slight treble boost.