Anyone out there with experience of the Goldmund Cartridge Interface

I am trying to find out what is known about the Goldmund Cartridge Interface, I have been in contact with Goldmund and they have no information now on that particular interface. I wonder if any of the members have used one these in the past and what they have to say about its effect on the essence of the music? How does it work on the musical signal, as this is a sealed 'black box' there is no way of knowing what is encapsulated within.
Any information gratefully absorbed.......