Fantastic tube amp. I probably didn’t use it as much as I should’ve. Only getting rid of it because my interest in tubes is somewhere else right now. Power tubes are starting to lose their fresh sound. Upgrade tubes are as fresh as when I bought the amp off another headfi'er. I spent all my time with the original tubes, so those have had some time on. I only tried out the upgrade tubes to test them before selling and they sound great. The left pot is bit scratchy at lower volumes and could use a little attention. The low impedance jack hu with sensitive IEMs. It’s not noticeable when music is playing. The high impedance jack is silent with my HD660S2.