Ok All you Schiit Eitr's

when I switched from USB to coax via the Eitr on my Hegel HD25 DAC it was probably the most satisfying upgrade I've done to my system.  And that was initially using a basic BJ coax.   A few months later I happened to have the chance to borrow an AQ Carbon coax.  I expected nothing much, but gave it a shot anyway.  It took only seconds to confirm that the AQ made a substantial difference for the good.  I sold my BJ coax and have never looked back.

What is this device for?

@maritime51- the Eitr is a USB to SPDIF converter.  http://www.schiit.com/products/eitr

Yes, but why use one?  I’m quite serious. Can you give an example? Thanks

There may be other advantages (galvanic isolation; equipped with a linear power supply) but for me it was simple...
the Gungnir DAC I bought did not have USB input (only BNC, RCA & Toslink for digital inputs).  At first I was using a Musical Fidelity V-Link 192 to convert USB to SPDIF to enable listening to USB output from a Macbook Air (now from an Aries Mini).  

USB advanced over the years.  I purchased the Eitr as an upgrade to the V-Link and because it incorporated Schiit's latest (5th gen?) implementation of USB, plus I really did want another piece of Schiit in the system :-)  Someone buying a DAC equipped with USB input wouldn't necessarily need the Eitr.