Ever wanted to know, what your phono cartridge sounds like dead flat??

Interesting! He says it can get the frequency response very flat, at least relative to the test record.  But then he says it can't help with the channel separation being no better than 30db. I wonder! The channel separation issue, if I understand it, has to do with the movement of the needle for each channel at a 90 degree angle (or whatever angle it is) relative to the other channel. Each channel inherently ends up coming in to the other channel, attenuated and reversed in polarity due to the mechanical arrangement. Seems to me this is something dsp could potentially address to some degree.