I have a DIY tube headphone amplifier with 4 PCL805 (RKV) and a 24-stage stepped potentiometer 50kΩ. The amp sounds absolutely great, no noise, no hum - but at step 4 (from left), he is almost too loud. Understanding question: Do I have to take a 20kΩ or a 100kΩ stepped potentiometer instead of...