Originally Posted by ambesolman
Chrono, I'm confused. You say a DAC downstream of an airport won't help but you tell mopkins that an external DAC will help?
I'm sorry if I gave that impression. 16/44 audio is all that you need for good music reproduction (i.e. no need for "HD audio files") but that doesn't mean any device that plays 16/44 is good.
When I said that iTunes is fine if you configure your system's audio output correctly (output 24/44.1 to avoid sample rate conversion) that assumes either going through a good soundcard, or sending a digital signal out to a DAC. What I meant is that iTunes is capable of bit-perfect playback, and you don't need to use another player to achieve that. Many people are under the impression they need to purchase software like Amarra or JRiver to achieve bit-perfect output, which is not true.
And "bit-perfect" output simply means that the playback software is not doing any sample rate conversions or anything else to the files (e.g. converting 44.1kHz files to 192kHz) not that the audio is "perfect" even if you are going through a bad onboard soundcard.
If you are playing audio directly from your PC, rather than streaming to another device, you will be going through its soundcard. Generally onboard soundcards are pretty junk. The manufacturer often lists good specs for them, but that is typically for the DAC chip they used, and not actually measurements from the output of the entire soundcard once it is in a running PC. Usually connecting a computer straight to your amplifier will have a lot of noise and often interference. Buying a better soundcard, or even better, sending a digital output to a DAC, should make a big difference to playback directly from a PC.
If you are using iTunes to stream audio to an AirPort Express, then you have bit-perfect playback of 16/44 files (CD audio) but anything else will be downconverted, because it can only
output 16/44, and when streaming to it, your system audio settings will have no effect. (because it's streaming the file to the AirPort, not passing through your soundcard, which is what the system audio controls affect)
From doing a couple of searches, I've come across measurements of both types of AirPort Express: http://www.computeraudiophile.com/content/466-measurements-first-and-second-generation-apple-airport-express/
It looks like all AirPort Express models will only
output 16/44, no matter what bit-depth or sample rate the input file is - and you want to avoid sending them files with very high sample rates. (176 & 192 look really bad)
It also seems that if you are using the analogue output, you want to get one of the old style AirPort Expresses, rather than one of the new ones. Even then, the analogue output seems good
, but not anything special. The noise floor could be better, compared to higher-end gear, for example. There is certainly potential for improvement if you were to add an external DAC to that, assuming it is a jitter-immune design.
But if you have one or plan on buying an AirPort Express, I would suggest trying it and seeing how it sounds to you - it might be good enough.