Audio is vague when earphones plugged in

On my PC (Windows 10), when my earphones are plugged in, the sounds are kind of fuzzy. It's hard to explain the phenomenon in words, so I'll describe a little experiment that illustrates the issue. When configuring the speaker balance as in the following picture (the default setting) and playing a song, I can hear the melody, but I can barely hear the singing. I cannot understand the words being sang, they sound like humming. Also, the music lacks clarity and is sort of distorted. When configuring the balance all the way towards right (as in the picture below), I can hear the singing clearly,

Question by snakile on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.