Krell, especially the FPB series on, and very especially the 600 is the furthest thing from hard and sterile when properly set up and nourished. It outputs what it is fed and CAN BE one of the most musical amps on the planet. It's like a 600watt Triode that can do things tube amps can only dream of. I wonder how much time the previous poster has spent actually listening to the 600, 350, or even the latest Krell series amps like the 700mcx when properly set up. I have heard that tubed preamps are amazing with the 600 but have not heard tubes on them myself. I can say I have a very smooth, tubelike component, the EAD Theatermaster Signature and the result with my 600 was magical. I could listen all day, and did at times. I sold my 600 because of listening to people like the above poster and bought Lamm's only to be disappointed by their inability to handle real life dynamic swings at non headbanger levels. The Lamms went out the door faster than any other amp I have owned. Gone were the rock solid 3d images, energy and BODY of the real thing. The only concern I would have in what you are considering is that Krell only accepts balanced inputs as well as proper impedance matching. Does the CJ output balanced? I think you should give it a shot - let us know the result.