measuring digital vs. analog cable noise

I have a musician buddy who called me and asked about quality in digital vs. analog coaxial cables. Specifically, he wanted to know the difference in sound quality between the two. That is, does it matter if you use an analog cable to transfer digital data. I want to help him test cables objectively without having to buy a bunch of new equipment, if possible. Does it seem possible to:

  1. create a “known track”
  2. burn it to a CD
  3. Play the CD in an external CD player with digital and analog coaxial output
  4. Use the test cables to connect the CD player to the PC
  5. Use Audacity to record the incoming CD signal with digital and analog coaxial input
  6. Record the various combinations of digital/analog coax
  7. Use Audacity to compare the known track to the CD signal and measure the SNR of the combinations

By using the same PC/CD player as controls, different cables can be tested.

What do you guys think?


It won’t make any difference. The higher quality cables allow you to go longer distances and survive greater interference without crashing. And it does crash. When you exceed the ability of the cable to carry the data, the sound will vanish. Before that it will be perfect.

That’s the up side of digital transmission.

It is possible under some really rare conditions to get a damaged bitstream, where the digital packages almost make it. That will be obvious because the show will sound like garbage and the damage will change greatly with any change in the environment. Bend the cable and the sound will either vanish or get perfect.

So you won’t need critical listening or distortion analyzer.