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What about the issue of jitter when using multiple Delta
cards?
There is always jitter, the question is whether or not it is audible.
Could I try testing one card internally clocked
vs. clocked from another delta?
I don't see why not?
Would jitter show up as
the difference between noise figure of each test?
In the spectrum analyzer plots made by the Rightmark program, jitter shows
up as sidebands near large sine waves. For example compare this plot showing
relatively high jitter:
http://www.pcavtech.com/soundcards/d...0_2496/thd.gif
to this similar plot showing relatively low jitter:
http://www.pcavtech.com/soundcards/d...T-2496/thd.png
The relatively high jitter in the delta 1010 plot had a known cause - a weak
cap in the power supply that was not properly filtering the DC power to the
audio circuits. This did not cause audible hum as such, but it did cause FM
modulation of the clock which led to the jitter.
Or will it even be measurable?
http://www.pcavtech.com/soundcards/d...010lt/2496.htm shows miniscule
but barely measuarable amounts of jitter. It could probably be made more
apparent with a more specialized test. However, its more than 120 dB down.
Jitter is inaudible when it is 100+ dB down, so the 1010LT tested was doing
very well indeed.