Very close tonally to the JJ 6L6GC tube with a bit more going on and easily justifying the extra cost. These are labeled as an STR tube. STR standing for Special Tube Request. When a buyer goes to the tube maker and delivers a specific set of specifications the tube goes into production as a S.T.R. One of the best know is the old Sylvania 6L6 tall bottles with the designation STR387. The TAD 6L6GC-STR is matched for plate current and transconductance and has the look of an old Sylvania. Using the old school U.S. style 6L6 plate design and a shiny black plate material they look like American manufactured stock. The sound is all there. The TAD is very percussive or punchy if you prefer. This makes them great for palm muting or “chunky” down-stroke rhythm playing. They break up a bit earlier than a JJ or Svetlana so you can get a bit nasty by digging in with your pick or clean things up by rolling back your volume control. They had the best tone biased at about 70% of rated plate dissipation. That’s about 21 watts at idle for a tube with a design max output of 30 watts. Both this tube and the TAD 6L6WGC-STR had some initial drift in plate current and required about 20 minutes to settle. I would recommend installing the tubes with an initial bias setting close to your target and check them again after ten minutes in play mode with a final check and adjustment after twenty minutes.