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iTunes Tune-up 11: Upgrading Sound Quality
I recently moved my iTunes library to an external hard drive. While it meant I could greatly expand the number of songs I could have in my library, the primary reason for the move was so I could upgrade the sound quality of the music I stored.
iTunes automatically compresses songs as they're imported. Compression helps fit more songs into the limited space of an iPod, but at a cost. The more a song is compressed, the more sonic information has to be discarded.
iTunes has a default setting of 128 kbps (kilobits per second) of resolution. This compresses a ripped CD track down to about a tenth of its size, with what's considered an acceptable loss of sound quality (to my ears, it sounds roughly equivalent to FM radio in a car). But if you'll be playing these songs through high-quality headphones or speakers, you may well appreciate the improved sound quality you get from a less compressed version of the file.
Changing the setting is pretty easy. Just go to the "Preferences" menu and select "Advanced." Under that tab, chose "Importing." There's a choice of file formats, as well as resolution. Some of the formats give you a choice of resolution. Don't worry about remembering numbers - Apple's helpfully labeled the choices with phrases like "Good Quality" and "High Quality."
In my case, I selected Apple Lossless, which only reduces the CD track to about half its size while retaining almost all the sonic information. If I wanted to move songs from one kind of player to another, I could have selected the MP3 Encoder as the import default. Sometimes when I have to convert something to an MP3 I'll change the setting so I can make the copy and then change it back.
The MP3 setting also lets you select compression rate. Remember that not everyone notices higher sound quality with a larger size file. If you don't hear a difference between a 192kbps and 160kbps MP3 file, then by all means go for the lower file size.
Also remember that this setting only applies to songs imported from CD. It has no effect on selections brought from iTunes. Purchased tracks come in as protected AAC files at 128kbps, or unprotected AAC files at 256kbps for iTunes Plus selections - regardless of what you choose as the default.
Now everything I import comes in as an Apple Lossless file, and personally, I can hear a difference in the sound. So with "unlimited" storage, I now have both song quantity and sound quality.
And what about all those low-rez songs already in my library? Stay tuned for iTunes Tune-up 12!