Chosen Solution
I have a Sanyo record player and tape deck attached to a computer, the music is not what it should be, with some instrumentation missing or very faint. One example is the harmonica/mouth organ on the Dean Martin hit “Little Ole Winedrinker Me”. The voices and most instruments come through as well as they should.
If you are feeding these signals into the mic in jack on your computer the “level” is off. Check the following. Turntable will need a preamp unless it has a line level switch. On your computer see if you can toggle the audio input to line level and not mic level.