I've played with every concievable passive pot, Bournes, Alps Blue Velvet, Alps Black Beauty, Penny&Giles, Dact Switched resistors, and transformers. Nothing has beat the sound of a series/ shunt LDR arrangment in the attachement, it has no contacts in the signal path, I believe that is the secret. The only stipulation that all these passive controls including the series/shunt LDR need I believe is,
- Low source impedence (cd player) <200ohms
- High input impedence (amplifier) > 50k.