Articulate argument from Tim Anderson on why 24-bit will not fix computer audio and why 16-bit is fine:

[What] are the limitations of 16/44 audio? We can be precise about this. Nyquist’s Theorem says that the 44,100 Hz sampling rate is enough to perfectly recapture a band-limited audio signal where the highest frequency is 22,500 Hz. Human hearing may extends [sic] to 20,000 Hz in ideal conditions, but few can hear much above 18,000 Hz and this diminishes with age.

In fact, despite the claims of audiophiles, most people cannot tell the difference between studio-quality output and an MP3 file, especially given that output is usually sub-optimal (car stereos, crappy headphones, TV speakers, and so on). And given that music is distorted beyond belief in all commercial recordings these days (to make everything sound ‘loud’, audio is compressed and peaks are clipped, wrecking dynamic range), upping the audio from 16- to 24-bits won’t make the slightest bit of difference in the vast majority of cases, even if you have high-end kit.

To my mind, as long as sources are offering ‘high enough’ quality lossy files (256–320 kbps AAC or MP3), that’s enough. Any move to 24-bit will just be corporate PR wankery—a pissing match that aims to snare users who think higher numbers are better. And I bet you’d get charged more for the privilege.