This is a follow up question to an issue I was experiencing, mentioned here. I'm really scratching my head on this one, as I assumed this was some sort of voltage issue on the power connection, but it seems it was an issue on the electrical s/pdif (coaxial) connection. I vaguely understand that an optical connection has no ground, so I now suspect the source of the interruption must have been some sort of voltage spike or drop on the ground connection?

A whatthifi article I found mentions

An optical cable doesn’t allow noise to pass from source to DAC circuitry like a coaxial can

but it also mentions

And, in our experience, compared to optical, a coaxial connection does tend to sound better. That's because it has greater bandwidth available, meaning it can support higher quality audio up to 24-bit/192kHz. Optical is usually restricted to 96kHz.

Any advice would be greatly appreciated.

  • 1
    I suspect that bandwidth limitation might just be due to the TOSlink protocol or DAC. At the purely physical layer, an optical connection is 100% electrically isolated, thus it is unable to transmit any induced electrical noise over the link. A coaxial cable is still capable of transmitting noise, either induced by source or from electromagnic interference.
    – Chris O
    Commented Apr 22, 2023 at 18:29
  • 1
    Regarding the bitrate, depends on the equipment, but here's some different opinions about that. Hard claims seem more difficult to track down: forum.psaudio.com/t/bandwidth-limit-of-toslink/3592ayrn.io/toslink-optical-connections-support-24-192khz-audio • the latter link is wrong about it being single-mode.
    – Ecnerwal
    Commented Apr 22, 2023 at 18:41
  • 2
    There's no living human that can discern 96Khz and 192kHz sampling rate. Human hearing declines fast above 20kHz, and 96kHz sampling rate is good into the 40kHz-range.
    – vidarlo
    Commented Apr 22, 2023 at 22:18
  • 1
    You don't need anything above 24-bit 48kHz unless you want to attract bats. Seriously, consumer equipment usually won't go higher anyway. Pro gear does, but we're still getting into either 'future-proofing' or 'audiophool' territory, depending on who you listen to.
    – Tetsujin
    Commented Apr 23, 2023 at 8:14
  • 2
    I’m voting to close this question because it's not about DIY Home Improvement.
    – brhans
    Commented Apr 23, 2023 at 20:25

1 Answer 1


Because TOSLink is plastic fiber optic streaming data, and thus immune to electromagnetic interference.

Unlike copper data transmission.

We networking folks LOVE fiber optic for that advantage, and while TOSLink is kinda low on the scale of data networking with fiber optics, it still has that advantage.

Obligatory TOSLink note - if someone tries to sell you a gold-plated TOSLink device, tell them to find another sucker. TOSLink being PMMA plastic fiber the only reason to gold-plate anything is to get AudioPhools to waste money on useless crap.

  • I did a little further research on this and while I think this is what you are implying, explicitly, it is likely the power fluctuations were dumping EMI to the ground connection, which in turn caused interference on the coaxial connection. Since toslink has no ground connection, it is impervious.
    – Wyrmwood
    Commented May 10, 2023 at 18:29

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