Digital XLR vs Digital RCA

This is somewhat of a controversial subject.  I have read some people state that AES/EBU XLR digital interface has design issues and not as good as RCA/BNC.  Others say that AES/EBU is far superior.

You can run both cables to the DAC at the same time and just A/B the source input on the DAC.

I disagree from experience. The quality of the digital cable, amount and quality of silver content, has dramatic affect in sound quality.

Agreed.  b4icu's statement is so very common from engineers who are only interested in measurement on scopes.

@williewonka - yes, I think I have used the KLE.  Well, it was the previous Eichmann Silver Bullet plugs (which are the same thing).   As with all cables, it is system dependent.  The sound was okay, but just a bit too bright for my taste and system.  I don't know that it really improved the sound for me. 

Amount of silver and type makes a difference in a digital cable? Really? Someone should tell those people that make cables that work in the 10's or GHZ or higher. They will be thrilled to find that out.

I have tested side-by-side pure copper, silver and silver-plated cable combinations.  The material used in digital cable absolutely affects the character of the sound.  This is just another medium you can use to help tune the sound to what you want.

I’m with @rego on this one - the type of connector i.e. whether you use IEC, BNC or XLR, is mostly immaterial when it comes to cable performance.

If you are looking at the cable performance itself (i.e. the wire), then this statement is generally correct.  However, when looking at digital cables, the type and impedance of the termination drastically affects the performance of the digital cable.  I have done many tests on different RCA connectors, using RCA that are designed specifically for digital (i.e. DH Labs RCA-75) as well as several extremely expensive and high end analog RCA (such as WBT, Furutech, etc.).  In all cases, a good low-cost BNC connector was superior to all RCA connectors.  The problem with RCA is the lower impedance, which allows reflections caused by the target S/PDIF receiver to flow back down the cable to the transmitter.  This causes distortion and timing errors in the source square waveform pulses.

In all my results, the audio high frequencies were not as well defined or clear with all RCA cables.  The high frequency extension and resolution was always better with a pure BNC cable/sockets. 

If you don't have true BNC connections on your source/DAC, the next best thing is to use a true BNC cable with BNC-to-RCA adapters on the end.  Nordost makes all their digital cables this way, but you can always do a DIY cable. 

I found the Blackcat BNC-to-RCA adapters are the best and have the highest resolution.