Recently switched my Sig X back into the live rotation while my D120 gets a power section retube. All 3 channels are fully functioning, but the lead channel is noticeably quieter than the clean and rhythm channels. I’ve rolled pre-amp tubes twice with known good 12AX7s, and theres no difference. Happens regardless of whether the footswitch is connected as well.
Could be just the channel volume setting. The clean channel will always be a little noiser than the Lead and Rhythm channels because it has no Master to attenuate the gain stage noise.
The lead channel has plenty of gain, it just operates at half the volume of the clean and rhythm channels when they’re all set to the same volume. I normally run the lead channel at about 9 o’clock for rehearsal and 10-11 o’clock live, but I have it set right now at noon and its still quieter than the rhythm or clean channels at rehearsal volume. The channel still sounds the way it should, just at a much quieter volume than it should for where the volume control is set.