Plan A: Shure E3s w/ optional triple flange. Better fit equals better sound!
Plan B: Assuming (hopefully!) that you already have a set of nice full-size cans (e.g. Sennheiser, Grado), spend the $150 on a nice headphone amp (e.g. Headroom, Creek, JMT Audio). Rip your CDs in Apple's Lossless Codec (ALC) and begin to hear a whole new level of performance from your iPod!
Good luck.
Plan B: Assuming (hopefully!) that you already have a set of nice full-size cans (e.g. Sennheiser, Grado), spend the $150 on a nice headphone amp (e.g. Headroom, Creek, JMT Audio). Rip your CDs in Apple's Lossless Codec (ALC) and begin to hear a whole new level of performance from your iPod!
Good luck.