What's happening everybody? I'm new to this forum and tube amps so here goes my newbie question. I recently bought a Rebel 30 and noticed a hissing sound coming from one of the tubes. I called Egnater and they said that I had one of the earlier releases that had problematic tubes. Well, in rapid fashion, they sent me a new set of el84's and 6v6's. The original set was JJ tubes. The new set are Ruby's. Do I have to bias these tubes or, are they plug and play? Please excuse my ignorance. I really love this amp and can't wait to hear it without the hiss. Oh and by the way, the guys at Egnater are real down to earth and friendly. It's nice to see that for a change!