I have the MZ2 and the MZ3. The MZ3 has a little more refinement and most likely is one of the best headphone amplifiers out there. As a preamp, it would have to be excellent. If you put in some 7062 tubes in place of the 12AT7, along with the great 12SN7 tubes, you are good to go. Excellent transparency, layering and bass quality. It would be fun to play it with some nicely modified Klipsch speakers since it also has speaker cable terminals.