I have a VTL preamp hooked up to a sonic frontiers sfs 50 amp using all nordost cables. I noticed a hum in the right channel and when I mute the preamp it pops. I've checked all the tubes and they are seated fine, I also checked my cables and they are also seated. My equipment is plugged into a Panamax power conditioner. Suggestions?
DC offset at the output of the preamp and then muting it could cause a pop. Also if you had a faulty ground connection inside one of your interconnects or RCA jacks that could also cause the hum. Swap the cables and see if it moves to the other channel.