Apple to offer 24-bit files? One thing to consider
CNN recently reported that Apple may soon start offering high-resolution 24-bit recordings through the iTunes® music store. While a lot of sites have posted opinions both pro and con about this possible upgrade, there's an important point (we think) that's been missed. And it concerns what happens when a 24-bit file meets a 16-bit processor.
It's out of spec!
Some critics claim that whatever improvements in sound quality would be gained from the proposed upgrade would be moot. Many computers — as well as current iPods®, and iPhones® — can only handle a maximum bit depth of 16 bits. So audiophile recordings down-converted from 24 bits by the playback device would lose much of the music's detail in the process (when you drop from 16.7 million bits to 65,000 bits, something's gotta go). In essence, critics say, you'd be back to where you started from with the 16-bit audio files currently offered by iTunes.
It's a valid point. But only if you let the device's resident DAC (digital-to-analog converter) do the processing.
There are a growing number of external DACs on the market that can address that problem. When you plug one of these into the USB port of your computer, it bypasses your PC's soundcard and processes the digital music file through its own DAC. So if you have a DAC that can handle 24-bit/96kHz processing, such as the NuForce Icon 2 desktop amp, (shown, right) then you should enjoy the full benefit of these higher quality audio files.
What about my iPod/iPhone/iPad?
From the research I've done, it's not clear yet what would happen when you synced your iPod and transferred these proposed iTunes-purchased 24-bit files over to your player.
Right now iTunes offers you the option of down-converting high-resolution files down to 128kbps in order to store more songs on your iPod. Since the iPod's built-in DAC can only handle 16-bit conversion it's possible that Apple might program iTunes to automatically down-convert purchased 24-bit tracks for transfer. If so, then the naysayers would be right.
There are several quality iPod/iPhone powered speaker systems and docks that bypass the player's built in DAC. With a Wadia 170iTransport, for example, you could send those stored 24-bit files to a 24-bit/96kHz DAC (either a stand-alone component, or one found in your receiver) and not lose any audio quality. The same would be true of Peachtree Audio's line of docking components (shown, left).
We don't know all the details about this proposed upgrade yet, but one thing we can be sure of. If higher-quality digital files are offered through iTunes, we'll have ways to help you enjoy them in all their audiophile glory.