My iTunes music library consists of iTunes downloads (256 kbps), and songs copied from my CD's (~400 – 1100 kbps). I have a dumb playlist containing a subset of these, which I sync to my iPod Nano (it doesn't have room for my entire library(. Also on the nano are other dumb playlists, each containing specific songs that are subsets of my main dumb playlist, which are tailored to my various workouts.
Recently, however, I've started listening to audiobooks on my Nano, which means I need to free up more room, so I'd like to replace all the CD-quality songs on my nano with 320 kbps versions (and I'd likewise like to still be able to use my various workout playlists). I thus had iTunes create 320 kbps versions of all my CD-quality songs. What I'd like to do is create smart playlists containing only songs whose bitrate is 320 kbps, and whose title matches a song found in a specified dumb playlist. This doesn't seem to be possible, but if it is I'd love to find out how!
Yes, I could just leave things as they are and, from within the Nano control window available in iTunes, tell iTunes to convert everything on my Nano to 256 kbps. But, since I have the space for 320 kbps, why not keep the maximum resolution? Granted, I might have trouble telling the difference….
Best Answer
For a portable device using headphones in a non-analytical environment, I'd just sync them at 128 kbps AAC.
You're really unlikely to notice.
You can do that in iTunes/[device]/summary in the last section, Options. It does that on the fly at sync [so takes a long time, first time] & keeps your iTunes at full rez, using copies to send to the portable device. You can set this separately for each device you sync, the low-bitrate dupes are kept in your iTunes Library once converted, but iTunes always plays the highest rate available.
It's effectively seamless
As a more generalised comment, & speaking as a professional sound engineer, I don't think tracks ripped from CD are worth saving at anything higher than 320kbps AAC*. Much as they were vaunted as being the 'perfect solution' for audio... in the 80's... they really don't have all that much data in them to benefit from anything above 320.
*or FLAC, but as iTunes doesn't handle FLAC, that point is moot.