I have three choices for digital input into my DAC:

  • USB audio 2.0, through the USB input
  • Toslink, through the optical input
  • S/PDIF, through coaxial (via HiFace2 adapter)

My understanding is that the third option is best, and I have convinced myself of this, more or less, sorta.

Why is this? How much is DAC-dependent (mine is a Moon 100D) USB requires no conversion, for example, but sounds noticable different.

1 Answer 1


I had a quick look at your device, it says the USB input is 16 bit / 48 kHz and that the device uses asynchronous sample rate conversion and 24 bit DACs @ 192 kHz.

S/PDIF and Toslink are identical at the bitstream level and both are consumer variants of AES3 which supports 16 or 20 bit at 44.1 or 48 kHz.

the HiFace2 says it has very good clocks, which should make no difference with short cable lengths and it says it does multiple sample rates up to 192 kHz and up to 24 bits.

So if the HiFace2 is running at 192 kHz and 24 bits and toslink is 16 bit 44.1 I can imaging the s/pdif sounding best and the toslink sounding worst.

Or if you are playing out a 44.1 kHz wav file it might sound better if the Moon 10D does the sample rate conversion than if you go 44.1 to 48 on the wire and then up to 192.

Worst would be a 48 kHz file re-sampled to 44.1 in the conversion to toslink and then to 192 in the Moon.

So it is worth knowing what the number of bits and the sample rate are at each point in the chain.

  • your answer is 100% right..well done good job
    – user114078
    Commented Dec 9, 2013 at 7:21
  • This is the answer. I hear the difference for 96kHz playback, and rarely use 192kHz. I swee these in the specs which would explain the poor USB showing; Bit-depth range 16 - 24 bits Bit-depth range - USB 16 bits Sampling Frequency Rate range 44.1 - 192kHz (up to 96kHz for TosLink) Sampling Frequency Rate range - USB 32 - 48kHz
    – Charles Pehlivanian
    Commented Dec 9, 2013 at 22:34

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