I sold my (160GB) iPod Classic months back and most of the items were 320bps MP3s and I had done several to Apple Lossless no problem. Is there space on the iPod? When I sold it I dragged out my old 32GB iPhone 4 and converted everything to 128 AAC so it would fit (it would hold about 2,500 songs in 320bps MP3s but I probably have 4,500 ripped for it). I only listen to it on long trips or occasionally in the car. While it is a different device (vs. the iPod Classic), I did have 2,500 songs in 320bps a few years back that I used a few times with an iPod dock in a spare system and did use it a couple in the car and didn't notice any difference in sound quality vs. the iPod Classic. I noticed the sound quality difference right away with 128 AAC. Not that it is the worst I've heard (the MP3s were ripped for an old Western Digital Media Player and it would only play them back as 128 MP3s for whatever reason and the AAC sounds better to me at that bit rate).