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TBOMK, certain tests (jitter) require one to place o-scope (or other test instrument's) probes on IC pins (or ckt traces). Can someone explain how one can do this and not affect the performance of the device. E.g., digital electronics require shielding, so taking the cover off and probing/testing effectively removes some of the shiled.

Up to 1997, we used to use the Meitner LIM Detector for jitter measurements, which operates in this manner. Yes, there is the problem you describe, as well as the fact that different designers will use different input signals to clock the DAC, meaning that the Detector's probe needs to be connected to different pins on the same chip in different designs.

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Also, how do you (Stereophile) probe today's ultra-small ICs (SOP, MSOP size, etc.). "Very carefully" or "We contract out to mosquitos" do not qualify as answers

Since 1997 we have been using the Miller Analyzer and, more recently, an Audio Precision System 2722, both of which look at the effects of clock jitter in the reconstructed analog signal, so this issue is not relevant.

John Atkinson
Editor, Stereophile