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.
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.