I've been using one for 2 years now. I could use a little more juice now and again but for the most part I enjoy it very much. Wonderful detailed presentation. Not as expressive or as much "there-ness" as my GTA SE-40, but still very good. Runs a little warm when played with much of any volume. I use it with the 550P phono and it's a great combo. I'd say for for it with the 850. I'd love one myself.