Question Regarding Pacific Microsonic HDCD Cables

They are filters.

There are pairs for the analog and for the digital.

You can see both kinds in the pictures section here:

http://app.audiogon.com/listings/da-converters-pacific-microsonics-hdcd-model-one-2013-05-16-digital-78759-austin-tx

They are designed to filter out the RF from both the analog and the digital signals.

Just like everything else that they make, they are WAY over-engineered. And work flawlessly.

I'd email Berkeley, makers of the Alpha DAC with your question. They may have an answer.

Ronaudio, wow that is very interesting to see. As you may know Pacific Microsonics Inc developed the HDCD audio technology. Then in Sept 2000, Microsoft acquired them. In light of this, I would venture to say that these cables you have were produced prior to 2000. So you have cables that are at least a dozen years old. How they're designed I don't know but obviously PMI had the HDCD format in mind. These probably work best with the HDCD signal path as compared to other cables available at that time. Best guess. Have you searched for any data or info on the internet?