Importing files to iMac

I'm importing files from discs to an iMac for transfer to a Sony HAP. I've been using iTunes (MP3 at 192 kbytes), but it's been suggested I should use uncompressed AIFF. But iTune AIFF is limited to 48 kbytes. What's the tradeoff between compressed and lossless and bit-rate? Should I look for software other than iTunes for encoding disc files, and if so what?