|Many music player manufacturers assume that their users encode 3-minute MP3/AAC/WMA files at a measly 128kbps. |
128kbps sounds awful, so you're probably encoding at least 192kbps, if not 224, 256, or even 320. I'm not sure what bitrate iTunes defaults to.
Obviously, the higher the bit rate, the bigger the file. If you don't mind the lower quality, you could re-encode all of your files at a lower bit rate. Or, you could leave your favourite tunes at a high rate and re-encode your meh tunes at 160kbps. This is kinda what I've been doing; I rip my favourite CDs to FLAC-lossless, and rip the others to 320K MP3.
Edit: THX 1138 beat me to it.
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