Is the optical out on the Airport express lossless?

Discussion in 'Mac Accessories' started by MortenMunchow, Jul 23, 2011.

  1. MortenMunchow macrumors newbie

    Jan 10, 2010
    I have attached an EMU0404 USB directly to my amplifier and have several options on how to transfer the signal to the EMU0404. One of them is the optical out on my Airport express but as lossless is extremely important for me it's mandatory that no manipulation of the signal what so ever is done in the Airport express. I know that potentially it is lossless as it is a digital signal but I want to be SURE. I use Apple lossless for my music files and want it pure brought to my EMU0404.
    Thanks for any insights :)

    /Morten Münchow
  2. miles01110 macrumors Core


    Jul 24, 2006
    The Ivory Tower (I'm not coming down)
    You seem to be confused between lossless file formats and lossless transmission mediums.

    Lossless file formats are lossless by virtue of their digital encoding. The structure and methods used to generate the file make it "lossless."

    Lossless transmission mediums do not exist. It is physically impossible to create a boundary between two different mediums across which there is no transmission loss.
  3. MortenMunchow thread starter macrumors newbie

    Jan 10, 2010
    I do know, that my text was not quite clear. Lossless in audio means that there is nothing done to the quality of the sound. It's like zipping the CD - you have exactly the same information after you unzip as before you zipped. MP3 always loose information even on the highest quality. You have less information after the information is unpacked as before it was packed.

    If it's transmitted digitally it's potentially lossless (by concept) regardless if it's mp3 or apple lossless format being transmitted. My question was if the quality of the sound signal is changed in anyway by the airport so that information is omitted to some degree in the information stream, leaving my EMU0404 with a degraded signal in some way to convert to analog compared to if I send the information directly into the EMU0404 by USB from the computer..

    Does my question make sense?
  4. MortenMunchow thread starter macrumors newbie

    Jan 10, 2010
    If a signal is digital nothing is lost in the information if the quality of the medium that carries the signal does not go below a certain level. Checksums and so on can check, if digital information is degraded during transmission.
    Your claim is true for analog signals.
    Is that not correct?
  5. 65535 macrumors member

    Jul 20, 2011
    By nature the singal is as good as it is strong. You'd have to measure packet loss between the devices.

    The digital signal will be of a much higher fidelity than anything else you use hardware wise. (Unless you're a studio, but I doubt that.)
  6. Foxer macrumors 65816


    Feb 22, 2003
    Washington, DC
    The AE isn't doing anything to you file when using the to slink (optical) out. The DAC on your system is getting the lossless file just as is on your Mac. This was a big deal for me and a friend of mine, and we did a good deal of research into this question.
  7. MortenMunchow thread starter macrumors newbie

    Jan 10, 2010
    Thank you everybody for all you useful comments. I'll stick with the optical solution :)
  8. AP Express macrumors newbie

    Nov 13, 2012
    Actually AirPort Express has only 44 kHz optical output. So if you have better files they will be converted to 44 kHz before sending to AE.

    But I prefer optical out of AE to optical out of MacPro.

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