airport express questions

Jax2 - Stereophile tested digital output of Airptort Express and compared to original uncompressed file they sent from I tunes and they are bit for bit identical with 255ps of word jitter.

APLC does not reduce quality of MP3. There is no missing bits in MP3 (nothing to interpolate) - it has 16 bit resolution. Bits are not lost - the musical information is (simplified). In order to play MP3 it has to be uncompressed first. APLC is decompressing MP3 and then compressing it to APLC format to decompress it to uncompressed MP3 ready to send to s/pdif out. No missing bits.

I have no idea why APLC sounds different to some people. Time to process data has nothing to do with it since it goes thru output buffer. It is possible that people compare sound from different devices like CDP versus computer while not every device is "bit transparent". Some CDPs have digital volume control or some form of DSP processing. In addition Itunes might have volume control enabled as well as equalizer. Finally it might be placebo effect.

Thanks for explaining that, Kijanki! I always thought of it as akin to uprezzing a graphics file, but as you are explaining it, it is not like that(?). I don't know how much stake I'd put in Stereophile's tests personally. I fI were to rely on their numbers and graphs I might never listen to tubes. I choose to rely my own ears. The file's that struck me as sounding distinctively different from each other were files ripped in EAC and converted to Apple Lossless, and to WAV and played in iTunes...vs. the same files ripped directly to those formats in iTunes. The EAC rips sounded better every time. This is with a previous version of iTunes and a very revealing system. I have not tried the same with the current version of iTunes, but will eventually try it with the MAX ripping software.

Jax2 - Itunes is not the best choice for ripping, I agree. I also agree that numbers published by Stereophile or other magazines are meaningless. I would even say that best tested devices have often the worst sound (there are reasons for that).

Stereophile reviews are pretty good but they tend to review only companies that advertise with them.

going to mp3, the bits are lost. compare file sizes. there is a reason why people use mp3 on ipod's because of the storage savings. also, it really doesn't matter what the AE uses to compress or manipulate the data from itunes, when it comes out of the AE, it will be the same as what it is feed.
an AE device is no different than the modems 30 years ago. the transmitting modem would send the data in a certain compressed mode (itunes on a mac) possibly with security built in, then the receiving modem (AE) would unbundle the data, strip the security bits,uncompress the data, and the remote data is byte for byte the same as the source.
this might be the only time i would agree with stereophile.
also, try xld if you are using a mac.
if you get a chance, listen to the amarra software for the itunes/mac combination. it sounded pretty good at ces.

Now, can someone tell me why, when running my airport express to a CA 840c using optical, that I periodically have an awful, glassy, fingernail-on-chalkboard sound?
Files are either alac or mp3 and with or without error correction when put on the confuser.
It doesn't happen at the same spot each time, but seemingly randomly.

Any suggestions?