I have a stock HD800 coming in. For now, I am using a modded HD800 (V version Bill-p) modded. This HD800V has a little bit less bass than the stock HD800 at the same voltage level, so distortion for the HD800V might be a little bit higher than stock (I drove the HD800V at higher levels to get the same volume at 39Hz). I'll redo these when the stock HD800 comes in. I ran these at two different levels, to so how the distortion characteristics changed. FWIW the HD800S has higher second order compared to the modded HD800. The modded HD800 has lower second order but higher third (and higher) order. Most people who have heard these headphones know that the HD800S does have a different sound in the lower registers compared to the HD800.