With the release of iTunes 9, there is a new option for Bit Rate Conversion to 128k AAC on the Summary tab when syncing an iPhone or iPod. I turned this one last night, and, after a long initial syncing/conversion process, it almost doubled the amount of free space on my iPod Touch! Is there a significant negative impact on sound quality? With my initial trials, including listening through headphones and through a speaker dock, I couldn’t tell much difference. There was a slight hissing noise apparent on one track from the new She & Him album ‘Volume Two’ that I downloaded from Amazon, but that may also be there on the original 256kb MP3 track.