Ralph, I assume you did this test on an ESI KSU. I find it interesting that, with the scope still connected to the page out, as soon as you connect it to the amp you see waveform distortion. I would think that even .05% occurring when connected to a 600 ohm input is indicative of poor design. Just for giggles did you ever try putting various resistive loads on the page output while looking at the waveform? Starting with maybe less than 600 and working up to 10k to see what happens?

-Hal


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