Just got the new Apple TV by FedEx today. I had been using an Airport Express (the newer 802.11n model) as a music server pulling Apple Lossless files from iTunes on my computer, and I intended for the Apple TV to take over this function (in addition to its other functionality). However, I was dismayed after some investigation that, not only is the new Apple TV not bit-perfect, its digital audio output is audibly flawed.
First, the bit-perfect part. The Airport Express is bit perfect as long as volume is set to maximum. I've tested this myself; when the Airport Express plays a DTS-encoded WAV file, my receiver's DTS indicator comes on and I hear music, indicating that the Airport Express is bit perfect. (As soon as I lower the volume even one notch, there's nothing but static, because the calculations required to perform digital volume control get in the way of bit perfect.)
Playing the same file through the Apple TV connected to the same receiver, I get nothing but static regardless of volume. I read on another forum that the Apple TV converts all audio to 16-bit/48KHz; presumably it's that conversion that precludes bit perfect. By the way, I turned off sound effects in the Apple TV, and it's still the same, no bit perfect.
So, the Apple TV is not bit perfect, but does that matter for the sound quality? AirPlay (formerly AirTunes) offers an easy way to do an A/B between the bit-perfect Airport Express and the non-bit-perfect Apple TV. By setting iTunes to output to both simultaneously, I'm able to do an A/B comparison simply by switching inputs on my receiver. My initial impression was that the two sounded pretty much the same even if one was not bit perfect. But then I noticed a slight click, almost like a tapping sound, in certain passages in piano recordings with the Apple TV but not the Airport Express (it's almost like the clicking sound you might hear through a digital receiver or processor when switching between inputs, but softer). I did have to listen closely, with headphones (AKG K702), and in a quiet environment, but it's consistently observable and repeatable in the exact same places in those recordings. I haven't tested with other recordings to see if the Apple TV does the same thing, but having observed the same flaw with two different piano recordings, it's clear that the Apple TV's digital audio output is flawed.
Anyway, I hope this information helps those out there looking for the Apple TV to do music duty. Stick to the Airport Express, at least for now.
