I have always considered the balance control on a preamplifier like a useless apendage – even worse, the extra componentry required for its implementation degrades the sound.
Why would anyone want a balance control? How many people actually ever use it? Come on, be honest, isn’t your balance control set dead-center?
Recently I may have come to a change of heart concerning balance controls and here’s why. They no longer add any degradation and, in some cases, they can be useful (despite my youthful stubbornness).
In days of old a balance control was another mechanically controlled variable resistor (like the volume control) placed in the signal path. Since we cannot make things better by adding a passive component (we can only make it worse) a judicious approach to adding components into the signal path has to be observed if we are to honor the sound quality.
But today, volume controls are handled electronically – and even if the electronics are only controlling a passive attenuator – the balance control becomes a free ride. So it’s a no-brainer.
But why use one? The room and the loudspeakers.
No room is symmetrical and it is the rare loudspeaker pair that’s matched any closer than 1dB and 3dB is typical.
A balance control that does not add any degradation thus becomes a necessary tool to achieving perfection.
Expect to see such controls in all future PS designs with volume controls.