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Audiophiliac
Avid Contributor I
January 13, 2007

Digital ouput and volume.....

I have been away from the forum for a while, but am still looking forward to getting a SONOS. :)

I have a question about the digital output and the SONOS volume control. HOw do they interact? I plan for an outboard DAC, and I would like to connect it straight to an amplifer without any kind of preamp if I can get away with it.....is this recommended? Or does the volume control effect the digital signal adversely?
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    salis
    Contributor I
    April 3, 2019
    Audiophiliac,

    At full volume or fixed output SONOS passes the digital stream unmodified. While it makes little sense to any analog units, the ZP80 digital connection will pass a DTS or Dolby Digital stream through to a digital input.

    When you lower the volume, the digital stream must be modified. This will destroy the DTS and Dolby Digital signal, because the bit stream is modified and is no longer a valid DTS or Dolby Digital stream. With enough processor power, the streams could be decoded and rebuilt with lower volume levels, but since this is a stereo audio device, there is no point in adding that expense.

    For the stereo audio signal, since we have a fixed number of bits to play with, some of the bits must be thrown away as the volume is lowered. Gradually, as the volume is lowered, the lower level information will be lost.

    Which digital amplifier are you using? I'm not familiar with any digital power amplifiers amplifiers that don't have some sort of input level control.

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    In the analog world, lowering the volume is not so hard on the music. The lower level information is gradually buried in the noise as the volume level is decreased. In the digital domain, the least significant bits are simply dropped. It would be possible to ease the digital degredation by use of "dither", but I don't know if SONOS is using this method.

    This is really helpful!

    Do you know how the volume control works in a typical Sonos speaker or the Sonos Amp?
    I guess the question is best described using the Sonos Amp (but applies to the Sonos speakers too - the Amp is effectively a combination of a simple amplifier and a Sonos Connect. When you change the volume via the Spotify app for example, does this control the volume of the digital stream (so the equivalent of the Sonos Connect in this example), or does it control the analog amplifier output (so the simple amplifier in this example)?
    Thanks in advance!
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