My preamp or poweramp seems to be making a noise

[Spaced Out Ace]

I'm not sure what the issue is or what is causing it. I run two Synergy Syn-2 preamps, some OS modules, and a Fryette Power Station PS-2A into one of my two cabs.

I noticed a noise while tuning up my guitar prior to playing. I'm terrible at describing the sound, but I hear it through the speakers. Sort of a "pffffp" sound would the best I can describe it.

Is it a bad tube or something?

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