Again with the hi-fi related post! But if you are in music production, I promise the training of your ear is just as important as any knowledge you have of audio gear and recording techniques. And having a quality system to listen to music on outside of the studio is important.
If you're following my posts detailing how to get audiophile-quality reproduction out of your computer using standard iTunes and other media players, in Part 1 you learned that the iPhone/iPod can play AIF and WAV files at 44.1k/16 bit CD-quality and ALAC files at 44.1k/16 as well as 24 bit. As was explained, you can import the full resolution files, or if you're not interested in the improved sound quality of these files for your casual iPod listening, you had the option of converting the large full-resolution files to 128kbps AAC's on import, thereby allowing much more music to be stored on the i-device, but at the lower sound quality of 128kbps lossy-compresssion. The new Apple OS now gives you the option of converting to 128, 192 or 256kbps on import. If you're using very good earbuds or phones, the converters and headphone amp in the iPhone 3GS and above is just good enough that you can discern a slight improvement in sound of a 44.1k/16 bit ALAC and the 256kbps version, but it is not drastic. Since you normally don't use your iPod for critical listening, and are often listening in noisier environments not suited to critical listening anyway, many would rather have more song capacity than the slight improvement in sound. But you can more easily hear the difference in quality between 256kbps and 128kbps. It's audible even on standard-issue Apple earbuds, and on high-quality buds and phones it's very evident. So this new option is perfect for better song capacity on the i-device with only a negligible loss in quality.
To change your hi-res files on import, connect the iPhone/iPad to the computer and launch iTunes. Hi-light your device in the devices list and the Summary page for your device comes up. Scroll down and under Options you'll see an option for "Convert higher bit-rate songs to: " and a pull-down menu with the different bit-rates. Choose the bit-rate you want, then click the Apply button on the right.
Rumor has it that the headphone amp and converters in the iPhone 5 will be a further improvement, possibly the same as are now in the iPad.
