For those taling about modding the S/PDIF out of a Touch a few thoughts:
the S/PDIF stream is generated in the processor chip itself, it then
goes to a reclocking flop, its in a very tiny single gate package, from
there it goes to a network of a couple resistors and a cap, which I
presume are doing an impedance match from the flop to the output. Do
NOT bypass that flop! The signal coming directly out of the processor
is quite bad, the flop reclocks it with the raw clock. 

As to putting in a BNC jack, it certainly can be done, but make sure
you use a real 75 ohm jack, BNCs come in both 50 and 75 ohm types, the
50 ohm types are far more prevalent than the 75 ohm types, if you just
get something that says its a BNC jack it will probably be a 50 ohm
type, it has to explicitely say its 75 ohms. 

As to the clock in the Touch being almost perfect, its not. Its a
normal cmos inverter and xtal oscillator, they are not "BAD" but they
are not great either. Its definately possible to get oscillators that
are MUCH better. And going with a better clock does significantly
improve the sound.

A while back I was doing a I2S out, clock fed back from DAC scheme and
decided to listen to the analog outs just for kicks, I was blown away,
the sound was way better than  normal. I actually expected it to be
worse, what with the issues of sending the clock over the cable I
expected the clock jitter to be worse. Even with the cable the clock
was better than the built-in one and it was quite obvious. 

So I would say that improving the clock is actually quite a worthwhile
mode if you can do it. Unfortunately there is VERY little room in there
to do it. 

John S.


-- 
JohnSwenson
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