So, inner groove distortion, what is it and how is diagnosed? I'm starting to notice more harshness lately with my system when it shouldn't be doing that.
I put a different tube in my pre-amp, a NOS G.E. JAN 5670W. I have other tubes to roll in, a NOS Western Electric 396A, Raytheon JRP 5670W 'D' getter and an RCA JRC 5670W 'O' getter (both of the 5670W are used pulls that test good), so I have some more experimenting to do. Running the same Adcom GFA-535mkII and Paradigm Mini Monitor V.5. I recently added a new phono stage, a Hagerman Bugle 2, which is a triple stage LM4562 with about 40dB of gain and matches my cartridge impedance of 47K right on. I don't have great interconnects between the output of the phono amp and line input on the pre-amp, so that is something I'd like to address. The cables on the 'table are fixed and are of decent quality. Between my pre-amp and power amp I'm using short Kimber Kable PBJ, so those are probably not a problem.
It's possible the slurring of vocals (like 'Ess'-sounds) and what-not could be related to the pre-amp tube or phono stage, but I doubt it. System sounds fine on some records and generally pretty good on CDs (my DAC is based on a Crystal 4398).
My suspicion is my stylus is getting close to done or I have reached it's limit. It wasn't a particularly high end to start (Ortofon OM5e) and it's a few years old. I can't imagine the alignment has shifted but I wonder. Maybe I'm tracking heavy or something. It does seem to get worse as the arm tracks in (at least I start to notice it more and it seems correlated to inside tracks on the record), which sorta does indicate an alignment issue. But I haven't touched it since setting it up originally. Just kind of stumped. Maybe my cart was never aligned right but I'm just starting to notice (e.g. the new phono stage being a considerable improvement now highlights the issue).