The Nagra HD Pre just sounds incredible and takes the HD amps up several notches. It is NOT subtle. I've heard the Classic Preamp in my home. I really liked it. I thought my Koda K10 was better a bit. Especially in how it portrays things in space, the weight on the notes, how finely everything is presented resolution wise and how it draws you into the music. The Classic pre was a bit better in dynamics and sheer resolution. The HD Preamp is even better than the best of the Koda and the Classic...just has a beautiful warmth, but with super resolution. Much more 3d like in imaging. Dynamics to die for. It just makes instruments sound like instruments. I don't know how else to say it. It's much like they are in your room playing. I've been glued to my system for a week now..seriously.
This is one killer good preamp.