When it rustles the input level is too low. - Open> Player. However, a higher level reduces the (stereo) channel separation heard (1 star deduction) and reduces the battery life of the player.
If it sounds dull - off> Dolby and select settings for iron magnetic tape.
If it works for me, it sounds like a very good music cassette or a good FM radio stations. No weaknesses or resonances in the audible frequency spectrum.
