check out this site, Head-Fi.org: Headphones, iPod earphones, portable audio, MP3 players, high-end audio . These people are Audiophiles and you can consider them as an equal to us when it comes to just about anything audio related.They can meet your expectations and take you about 50 levels above that. Hope this helps.

I am also a member there and let me warn you, These people are on an endless quest for audio perfection, and I can say myself that they have led me to spend about $500 or so on my portable setup.

iPod is actually quite bad when it comes to Sound Quality.