Ohne es selbst überrüft zu haben, hier eine gelesene kritische Stimme:
"A long time ago - around 15 years, as I recall - when this hooey about "balanced" tubes started to really take off, I did an experiment:
I installed a PI balancing circuit in about a half-dozen of my customer's amps (they were interested in the results too, and I didn't charge anything for the mods) and told 'em to twist the knob on the balance pot under different playing conditions (loud, soft, clean, distorted, bassy, trebly, etc.) until they had it set where the amp sounded best to them most of the time, and then play it that way for a week or two to make sure they didn't need to adjust the control any more and then bring the amp in so I could take readings off it.
Know what? NOT A SINGLE GEETAH-PICKER HAD TUNED HIS AMP'S PI STAGE SO THAT IT WAS BALANCED! Not one. So don't waste your money, folks - it's snake oil."