looking for advice to mitigate inner groove distortion

I also suspect mistracking ... bit if it is then there may we’ll be groove damage and in that case nothing will fix it. Is this just on one album, or on many, including brand new ones?

Just get $100 new cartridge and try it with it. We can't see or hear what you do. It's inexpensive experiment.

lewm

One could argue about alignment all day but I strongly doubt that misalignment or Stevenson alignment can account for this problem.

It's much easier to get phono cartridge alignment wrong than it is to get it right. If LPs exhibit inner groove distortion, alignment is the first place to look if you want to be methodical. You're likely to be just chasing your tail if you don't first confirm that the alignment is correct.

A distortion analyzer can easily show the results of a misaligned phono cartridge.

Cleeds, I don’t think we are listening to each other. I am saying that I do not think that the particular symptom reported by the OP is due to misalignment. I did not say that misalignment could not cause distortion, although I have my private doubts about the audibility of such distortion. You say that misalignment can be detected on a distortion analyzer. Do you know of any published data to that effect? I would be interested to read any article about that, but I have been unable to find such an article after doing a computer search. By the way, all three of the popular alignment algorithms result in some degree of tracking angle error at the inner grooves, as you probably know. Of the three, the innermost null point for the Stevenson alignment is closest to the spindle. For that reason inner groove distortion with the Stevenson alignment is probably not worse or significantly worse than that of any of the others.But this is a minor point. I agree with you that most of us have made a tiny error here and there in aligning our cartridges. That means nearly none of us is listening to a perfectly aligned cartridge.

I think that the OP might be experiencing an effect of the Rega motor on his cartridge due to EMI. The fact that it gets worse as the cartridge approaches the spindle is consistent with that, just as it is consistent with inner groove distortion. Furthermore, it seems to me that I recall that Rega motors are known to interfere with some cartridges, in particular Grado cartridges, as I recall. But I could be wrong. Checking out the role of the motor in this phenomenon is actually easier than checking tonearm alignment.

IME, inner groove distortion can be caused by many things.  Not sure how old your cartridge is, could be the suspension is worn and you need a new cartridge, or in your case a stylus replacement.  Could be the way the diamond is cut does not like your stevenson alignment.  Try a new stylus.