Advice on a good Digital Coax Cable to run between my Transport and DAC?

Avoid Acoustic Zen MC2 because it is 110 not 75 ohm rated coaxial cable / connector.

@sls883  Out of curiosity, I called the Cable Company to inquire about impedance standards, as these are universally followed by industrial manufacturers. There are no exceptions—for example, 75 ohms for S/PDIF and 110 ohms for AES/EBU. These standards are regulated by the IEC, which governs the manufacturing requirements for both audio components and their associated cabling and terminations.

A knowledgeable gentleman kindly informed me that the information posted on the website—specifically that the Acoustic Zen MC2 is a true 110-ohm cable—is a mistake. It should be stated a true 75 ohm instead.  He confirmed the impedance standards I mentioned earlier.  Again, no exception.

He also added that while cable impedance is standardized, the terminal connectors used for coaxial cables are not always a perfect 75-ohm design. Small variations can exist—for example, a connector might measure 74 ohms—which could cause minor high-frequency roll-off. However, he confirmed that the connectors used on the MC2 are indeed true 75-ohm designs.  This also clarifies the misinformation in the previous thread https://forum.audiogon.com/discussions/acoustic-zen-mc2-110-ohm

@soix  What do you know about impedance mismatch and industrial standards?  My observation is absoutely little to nothing. It’s disappointing to see advice being shared from a literally ignorant person without a proper understanding of audio. Unfounded recommendations don’t help the Audiogon community grow in knowledge. 

@sls883 

A further investigation / clarification to the impedance mismatch issue. Impedance mismatch causes signal reflection, which in turn has the following two impact on the signal quality.

First, mismatch loss, which is audible signal loss due to reflection, can be quantified as -10 log(1-|CR|^2) dB, where CR = Coef. of reflection = (ZL-Zc)/(ZL+Zc), ZL = load imp. And Zc=cable imp.  So, using the example if MC2 coaxial is a 110 ohm into 75 ohm load, CR = 0.19 and mismatch loss = 0.16 dB.  So if the signal loss due to reflection is only a fraction of a dB, why is imp. mismatch such a big deal?  The answer lies in the time inaccuracy, i.e., known as jitter, caused by the signal reflection.

Second, jitter can be quantified approximately as

|CR|x (round-trip delay due to reflection) x (edge sensitivity)

If you have 5ft rca cable, which as a typical signal propagation delay of 1.5 ns/ft, and assume edge sensitivity is 1.0 for the cable w/o loss of generality, the jitter can be estimated as =.19 x (1.5x5x2) = 2.9 ns = 2900 ps, which is humongous in hi-fidelity signal chain reproduction.  In general, 100 ps jitter or less is considered good and audible level of jitter is around 200-300 ps.  The high-end gear typically has around 10 ps.