Okay, don't jump off the dock unless you can swim here, JEb. Are you aware of the danger in working inside that chassis even when the amp is unplugged?
Do you know how to drain the caps?
Green Lantern wrote: "As long as you get the type of power tubes you're supposed to get for that amp, you don't have to bias when you change them."
It may be that one can safely replace those 6V6's in this amp without rebiasing. In the stock configuration, the bias point is set so cold that perhaps ANY 6V6's will work 'safely' in there. Whether or not the sonics stay the same is the question. Inorder to maintain the sonics----if the sonics are pleasing to you---one must replace the 6V6's with new tubes that are graded to the same performance specs. This is not matching. Matching is pairing up tubes that have similar performance specs. Tehn, once the bias is set for the soncis that one prefers, using tubes with those same performance specs...same 'grade'....willmaintain the soncis....IF...big IF....the ap is still operating in themanner that it was when the bias was set. Imho, it is good to know what current draw an amp is functioning at. Experienced ears can set these amps' bias by ear in a p inch...but I still like to takemeasurements when I can to understand the current draw and ultimately the plate dissipation factor. Plug and go....doable. YOu just risk suffering cold bias sonics---why run a tube amp that sounds like a sterile solid state amp, right? ---- or burning an amp down....unless you are experienced enough to know how to listen and look to set the bias 'on the fly'.