Most consumer audio products adhere to established standards when designing digital interfaces and connections. Specifically, the impedance specifications for cables and connectors are 75 ohms for S/PDIF and 110 ohms for AES3 . Using cables or connectors that deviate from these standards can lead to impedance mismatches, resulting in signal reflections and increased jitter.
I mention this because several individuals have endorsed the Acoustic Zen MC2 cable, which is described as a true 110-ohm design . These users have reported no noticeable degradation in sound quality. However, their positive experiences may not necessarily apply to your specific setup. Therefore, I advise adhering to standard specifications to minimize potential issues.
Additionally, it's worth noting that the MC2 cable is constructed from pure silver. Silver conductors are known to produce a brighter sound in the upper registers, which can give the impression of enhanced detail and treble or upper midrange performance. Whether a silver cable complements the Harmony DAC depends on the overall system synergy.
Lastly, pay attention to the capacitance rating of the cable. An S/PDIF cable with higher-than-normal capacitance can function like a low-pass filter, attenuating high-frequency signals and rolling off the treble. This phenomenon has been empirically observed and reported by end users on multiple occasions. Practically, you want to avoid capacitance rating over 200 pF/m (or 60 pF/ft) or longer run to avoid any audible degradation in highs.