"mc" said:

Indeed, because of the elimination of EMI with optical, if anything Sony
should be recommending the use of the optical input for critical
adjustments.


I was wondering the same thing. If it's digital, why isn't it absolutely
bit-for-bit identical both ways? The optical input would be immune to
electromagnetic noise, and that should be the only difference. Normally
they should be indistinguishable because electromagnetic noise strong enough
to disrupt a digital signal is rare.


A common mistake.
The S/PDIF signal is analog in nature.
Just as with RF signals, an incorrect termination might cause
reflections ( "a bad SWR") which, in turn, are said to cause jitter.

Jitter doesn't have to be a problem per se.
When the incoming signal in e.g.a DAC is reclocked for instance, the
jitter must be very extreme to have any effect at all.
If that extreme is reached (not likely), the result will be silence,
not degraded audio.

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005