I think it was 1999 or 2000. You might want to check with Garth at Musical Surroundings. I seem to recall the old Ruby being around .2mv output, a very low number, and why I chose the Reference over it when I bought a Reference in 1998. When the Ruby 2 came out, I auditioned it, liked it a lot and upgraded at that point, and I seem to recall that being in early 2000. Hope this helps.