optical or coaxial audio cable?

It's my understanding that over time, the coax will be the better choice. Glass fiber WILL develop microfractures each and every time it moves, rendering the cable more and more opaque. After a while, its ability to transmit data will degrade. The metal coax should sweeten over time, as the crystals in the wire align. This is all assuming that you keep your coax terminal connections clean and fresh, of course.

So, what you are saying is that all of these Fiber Optic cables that various phone companies are burying for long term use will all have to be dug up and replaced on a regular basis ? Sean
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I am running both optical and coax from my Sony transport. They are indistinguishable now, but only after I did mods to the digital output circuits to improve jitter. With the right cable, the coax can usually be better, because it avoids the optical to electrical conversion stages, which add both noise and jitter.

When we put the latest generation of Trident missiles into existing submarines there was concern that the hundreds of feet of 25 year old coax cable between the missile and the fire control system would never work at ten times the frequency for which it was originally intended. I participated in tests which revealed that the digital pulses were indeed thoroughly mutilated as they traveled through the wires...but, after reclocking and regeneration by the well designed line receivers, information was transmitted flawlessly. If digital audio equipment were properly designed (and I think that some is) this whole issue of digital transmission fidelity wouldn't matter.

Sean, I think the referance was to degredation of optical whenever it is disturbed. Buried optical lines remain untouched and unaffected.