I took delivery of a SDG 5E3 Proluxe today. The OT is beefed up to handle both types of tubes. It also has adjustable bias. Sounds great with the set of NOS tubes I put in (Jan Philips 6L6WGBs, RCA 12AX7, Mullard 4024) and Ruby 5AR4 rectifier. I set the bias at about 33-35 mA for that combo. I want to try 6V6s, but worry that the 5AR4 isn't right and don't want to risk any damage. Which Recitifier should I get for the smaller power tubes? Also, it seems to sound better with the 12AX7 in the preamp slot and the 4024 (12AT7) in the PI. That's backwards from the stock 5E3 config, but it sound's better and even cleaner to my ears than the other way around. Is it possible that the PI can induce more distortion than the preamp? I didn't get to crank it, but did run it up to about 5-6.