So the PrimaLuna DiaLogue Seven amps are stereo units run with channels running in parallel at the output taps with a special type of feedback to balance out the channels. So why the big rise in distortion (fig 12, pg 92) at the frequency extremes? If a "normal" stereo tube amp is connected up with the channels run in parallel, how much worse is the distortion? Art didn't seem to mind the DiaLogue's performance, so I wonder if the distortion is more of a "bench issue". I have used tube amps in this fashion and they do sound different in mono vs. stereo (in mono the soundstage seems larger yet a little diffused.