6.Why is the sound from the E12A skewed to one side at low volume?

A: This is the behaviour of all analog potentiometers (volume controls).  Please switch to low gain for sensitive earphones.  All is normal if the channel balance is audibly normal at normal listening volumes.If channel balance at very low volumes is vital for you, please consider choosing our Q1/E17K/E18 series headphone DAC/amps with digital volume control.