Running Win 10 w/ Realtek High Def Audio seems attempting to use mic imput from stereo to rec vinyl, but that activates internal mic and sound becomes badly distorted (as well as picking up ambient sound from room) can't seem to find the correct change of setting
You need to use a line level input (or setting) Vinyl and most preamps in general output line level, be it balanced +4dB or unbalanced -10dB, both of which can overdrive microphone level inputs and will distort regardless of the record volume setting.
A line-to-mic pad (attenuation) is another option) but most are mono.