On Mon, 01 Sep 2003 00:13:46 +0100, Chris Isbell
wrote:

On Sun, 31 Aug 2003 21:09:45 GMT, (Stewart
Pinkerton) wrote:

[Chris Isbell wrote]
Could you possibly explain why a separate DAC is a very bad idea,
please? (I have just purchased one!)

Jitter. The CD system was never intended to have separate transports
and DACs, so the embedded clock in the S/PDIF datasteam is not robust,
and is prone to adding jitter. Not a problem for a well-designed DAC,
but far too many so-called 'high end' DACS have input receivers which
are quite stunningly incompetent at suppressing jitter.

In a standalone player, a single low-noise free-running master clock
placed close to the DAC chip controls the entire system, leading to
lower jitter than is possible from a separate DAC with it's PLL clock.

Thanks. So if the DAC regenerates the digital signal with its own
clock then jitter should not be a problem?

Correct, although this is extremely rare. Your SRC does however do
exactly that.

My DAC just happens to be
preceded by a sample rate converter; it's a Behringer SRC2496.
(Fortunately it's not a high end DAC so it may be reasonably competent
in handling jitter on the S/PDIF data stream. ;-)

If the SRC has a good clock, then you may end up with a good system.

If there were a problem, how would it affect the sound?

You would hear a slight 'smearing' of the sound, as jitter generates
FM distortion, just like wow and flutter but generally at higher
frequencies.
--

Stewart Pinkerton | Music is Art - Audio is Engineering