The Audio Precision Analyzer allows to dial in various amounts and types of jitter on its digital outputs (AES3, SPDIF, TOSLINK) so one can test at which jitter levels (pathological cases, mind you) any modern DAC starts to loose sync. And before it does, one can measure degradation with the J-Test signal. As far as I can see, Amir uses the J-Test mostly over USB where it is almost useless (and thus seldom shows serious degradation). J-Test was designed to be used with standard DAI connections (AES3, SPDIF, TOSLINK) where the clock is recovered from the signal.
I seriously doubt the problem some DACs may have with some CD transports/players is any related to jitter. CD transports/players are not jitterbombs and DACs should easily handle this in any case.
And to create relevant levels of jitter in the cable itself there must be a significant line termination impedance mismatch at the sender and the receiver, plus the cable must just the right length that the reflections (first back from receiver, then forward from the sender again) line up with the edges in the waveform. Another source of jitter (of a different type) would be truly horrible dispersion characteristics of the cable, with time-of-flight vs frequency being very irregular, not constant, which could severely round off the edges.