Edit: the real issue is background radio interference.

[raif71]

Tin T2

 

[Human Bass]

Now, after trying more phones, cables, etc. The real issue Im having, that is rather minor, is a very faint radio interference, especially when the pot is all the way down and all the way up. Yup, down, volume "zero" has the same interference as all the way up. Between those extremes, it disappears.
@JohnYang1997 could you explain what kind of effect the volume pot causes when it is all the way down and up?