5 ms·

Since it’s USB, it has to be the DAC generating the hiss. No amount of electrical interference can do anything to the digital audio going Ofer USB.

saxonww 8y ago
I thought so too, but regardless, with this same device there is no hiss when connected via optical. So if I had the option, I'd be using optical vs. USB today, which was what the GP asked.
- Applejinx 8y ago
  Logically, it seems like if you had a USB-optical dongle you would have no further trouble. I don't know if there is such a thing, but I do know that in that situation all the 'it's digital, so it should be perfect' talk becomes somewhat true. You'd be converting from USB to optical, at which point you'd break the ground connection which would be where your hiss is coming from (assuming it's still noiseless when still being used with optical). Then, your concern would be jitter and whether the added conversion is adding lots of jitter to the equation. Your DAC might (or might not) be good at rejecting jitter noise. I've got a Lavry DA10 that's exceptionally good at rejecting jitter (in crystal mode), but that's mastering grade and maybe overkill for you. It wouldn't add literal noise, but it's also possible for the USB connection to be more jittery than a different computer making the optical connection. That's partly hardware and partly software design (controlling how the data stream is buffered, and associated things that might slightly modulate the audio data clocking). So a change in computer feeding the DAC could also substantially affect the 'sound' of the DAC, as well as the noise issue you observed.
  - saxonww 8y ago
    I agree, that should work. I haven't seen USB-optical devices that weren't straight media converters though. Everything that converts USB to spdif is advertised as a DAC, so I'd have two DACs. This isn't a huge issue for me, it's just an example of where I'd prefer to use optical. If it ends up bothering me such that I need to fix something, I'll 'fix' the motherboard.
uxp100 8y ago
But it sounds like its the same DAC, which was hiss free with optical. So it's not the DAC "generating" the hiss. Rather electrical "interference" making it over to the analog side from the digital side. So it's the DACs fault, but maybe it's fair to say that it's harder to make a good DAC when USB is how the data is being delivered. I'm sure a high end USB DAC doesn't have this issue, but I'm pretty impressed with my cheap offbrand optical DAC that was $11. I'm guessing I would not be so impressed with the $11 USB version.
- dwaite 8y ago
  A higher quality USB DAC either has to do quite a bit of signal clean-up, and may use its own power supply rather than trying to clean up the USB power from the computer. Optical has the benefit of always being electrically isolated.
chipotle_coyote 8y ago
The electrical interference can't do anything to to the digital audio, but interference on the USB cable can potentially be picked up by the analog amplifier circuitry in the DAC. I had a particular combination of headphone, DAC and amplifier years ago that I could hear electrical noise on when no music was playing.
- Applejinx 8y ago
  Absolutely. I work as a sound engineer and have used lots of things of this type, and it's particularly easy to understand how a USB connection to the computer would wreck the sound of a cheap (sub-$1000, not professional) DAC. Optical digital means perfect isolation from the ground plane of the computer. It's that simple. The DAC can do whatever it needs to manage its own noise levels, but you're pretty much guaranteed a huge difference from entirely decoupling the DAC from the computer's ground plane. That electrical interference can do a surprisingly enormous amount of damage to the analog circuitry of the cheap DAC, which itself is probably not very resilient at rejecting any sort of electrical interference.

saxonww 8y ago

I thought so too, but regardless, with this same device there is no hiss when connected via optical. So if I had the option, I'd be using optical vs. USB today, which was what the GP asked.

Applejinx 8y ago
Logically, it seems like if you had a USB-optical dongle you would have no further trouble. I don't know if there is such a thing, but I do know that in that situation all the 'it's digital, so it should be perfect' talk becomes somewhat true. You'd be converting from USB to optical, at which point you'd break the ground connection which would be where your hiss is coming from (assuming it's still noiseless when still being used with optical). Then, your concern would be jitter and whether the added conversion is adding lots of jitter to the equation. Your DAC might (or might not) be good at rejecting jitter noise. I've got a Lavry DA10 that's exceptionally good at rejecting jitter (in crystal mode), but that's mastering grade and maybe overkill for you. It wouldn't add literal noise, but it's also possible for the USB connection to be more jittery than a different computer making the optical connection. That's partly hardware and partly software design (controlling how the data stream is buffered, and associated things that might slightly modulate the audio data clocking). So a change in computer feeding the DAC could also substantially affect the 'sound' of the DAC, as well as the noise issue you observed.
- saxonww 8y ago
  I agree, that should work. I haven't seen USB-optical devices that weren't straight media converters though. Everything that converts USB to spdif is advertised as a DAC, so I'd have two DACs. This isn't a huge issue for me, it's just an example of where I'd prefer to use optical. If it ends up bothering me such that I need to fix something, I'll 'fix' the motherboard.

uxp100 8y ago

But it sounds like its the same DAC, which was hiss free with optical. So it's not the DAC "generating" the hiss. Rather electrical "interference" making it over to the analog side from the digital side. So it's the DACs fault, but maybe it's fair to say that it's harder to make a good DAC when USB is how the data is being delivered. I'm sure a high end USB DAC doesn't have this issue, but I'm pretty impressed with my cheap offbrand optical DAC that was $11. I'm guessing I would not be so impressed with the $11 USB version.

dwaite 8y ago
A higher quality USB DAC either has to do quite a bit of signal clean-up, and may use its own power supply rather than trying to clean up the USB power from the computer. Optical has the benefit of always being electrically isolated.

chipotle_coyote 8y ago

The electrical interference can't do anything to to the digital audio, but interference on the USB cable can potentially be picked up by the analog amplifier circuitry in the DAC. I had a particular combination of headphone, DAC and amplifier years ago that I could hear electrical noise on when no music was playing.

Applejinx 8y ago
Absolutely. I work as a sound engineer and have used lots of things of this type, and it's particularly easy to understand how a USB connection to the computer would wreck the sound of a cheap (sub-$1000, not professional) DAC. Optical digital means perfect isolation from the ground plane of the computer. It's that simple. The DAC can do whatever it needs to manage its own noise levels, but you're pretty much guaranteed a huge difference from entirely decoupling the DAC from the computer's ground plane. That electrical interference can do a surprisingly enormous amount of damage to the analog circuitry of the cheap DAC, which itself is probably not very resilient at rejecting any sort of electrical interference.