I've got a preamp with a volume jack on the rear panel and I'd like to see if I could use it to control the volume and also use it as a standby. According to the manufacturer, the value of potentiometer which would work best in a volume pedal would be 47K-50K log. So far, I've been unsuccessful at finding one. I've seen potentiometer values of 500K, 250K and 25K, but nothing in the range I was looking for. I thought that I could get an old style Ernie Ball pedal, without the circuit board, and find a 47K-50K potentiometer that would have a long enough shaft and try to get it to work, but really that's just an idea and I don't know if it would work. So, I thought I'd come here to ask if anyone knows of a solution for this. Another idea is to get an on/off switch type of pedal to toggle the volume. Again, I'm unsure of the type of switch I would need. If anyone knows of a pedal that would work or another solution that would be great. Any other thoughts would be appreciated as well.