Q: I would like to import my CDs into my library at 320kbps in order to preserve them at the highest possible quality. However, I would like to transfer them onto my iPod at 128 kps in order to fit the most songs onto it. Do I have to rip my CD’s twice – once at 320kbps, and again at 128kbps, or can I change the bitrate of the tracks when I transfer them onto my iPod? If I do have to rip the CD’s twice, is it possible to have 2 separate libraries – one for the 320kbps bitrate, and one for the 128kbps?
A: Unfortunately, the only iPod model that offers on-the-fly conversion during transfer is the iPod shuffle, which offers a fixed downconversion to 128kbps. Other iPod models do not offer this option, and will simply transfer your tracks onto the iPod at their original bit-rate and format.
It is possible to maintain two separate iTunes libraries, although keeping them both up to date in terms of playlists and other metadata may become more trouble than it’s worth. To do this, simply hold down the SHIFT key (Windows) or OPT key (Mac) when starting iTunes, and you will be prompted to choose or create a new iTunes library. You can toggle back and forth between libraries using this method.
That having been said, you may want to consider whether you really need 320kbps music stored on your computer if you are not going to be transferring it to your iPod. Most of the significant quality differences between different bit-rates are only noticeable when listening to music through a good set of earphones in a relatively quiet listening environment. Unless you also plan to play your music directly from iTunes through an expensive home audio system, or use quality earphones with your computer itself, the 320kbps tracks on your computer will simply be an unnecessary use of storage space. The greatest benefit from the higher bit-rate will likely come from having these files also stored on your iPod.
Our usual recommendation when discussing bit-rates is to do some proper blind comparisons to determine what bit rate you find acceptable for your own use, since this is an entirely subjective decision. There is seldom any point in encoding music at a higher quality than you can actually hear in your normal listening patterns, and you may find as a result of this that a mid-range bit-rate such as 192kbps or 256kbps is a more than acceptable compromise between iPod capacity and having to maintain two separate libraries. Further, there are many users that find even 128kbps to be perfectly acceptable for any listening conditions.
So before you decide to go to the trouble of using a higher bitrate and maintaining two libraries, your best bet is to try ripping some of your favorite tracks at different bitrates and play them “blind” (without knowing which is which) and try to determine at which point you can actually hear a difference in sound quality.