...for some classical recordings, the strings have some silbius or distortion, that are corrected by going to 4.0. I am still running it at around 2.2, but was curious why it is that wayThere are several possible causes, including various setup parameters and phono stage slewing distortion, but here's one cause I'm certain is involved to some degree in your system.
Every stylus has a contact radius, which determines the minimum size of the groove modulations it can trace. When a stylus encounters modulations smaller than it is, all it can do is scoot past the tops, playing part but not all of the waveform at that frequency. This necessarily results in clipping of the waveforms at these higher frequencies and perhaps in the momentary loss and regaining of stylus-groovewall contact, all of which we hear as "sibilance". The larger the stylus, the lower the frequency where this will begin to occur.
The contact radius of the 103's conical stylus is much larger than the contact radius of styli in some more modern cartridges. Finer stylus profiles trace smaller modulations (ie, higher frequencies) cleanly, and do not start "scooting" past small groove modulations until higher frequencies.
Increasing your VTF to excessive levels will not make the stylus fit into modulations smaller than it is, but it may mitigate the resulting distortions in a couple of ways:
1. Increased pressure between stylus and LP assures that the stylus will not lose contact, which makes the (unavoidable) clipping of too-small modulations as smooth as possible.
2. Increased pressure between cantilever and suspension is smothering higher frequencies, much as soft earplugs block higher frequencies while letting lower ones through. In effect, you're using excessive VTF as a HF rolloff filter.
If you listen to a lot of this kind of music, and the distortion bothers you, I'd suggest that your next cartridge be one with a line contact or micro-ridge stylus. All else being equal, they reproduce HF's more cleanly than conical or elliptical styli.
