I have recently tried the Wadia 850 CDP(with the top of the line upgrade from Great Northern Sound) and a newer 861 Basic CDP. I had no problems running them direct into my amp or with my Pass X-1 preamp. I thought that the modified 850 worked perfectly running it direct into my Pass Labs X-250 power amp. It was very clear and detailed sounding, never harsh, and had great dynamics and bass slam. It was an improvement over the stock 861 CDP. I do not think that you can get better sound than the modified Wadia unless you pay two or three times the price. If I had the money, I would be buying one myself.
Happy Listening.
Happy Listening.