I tried 43 ma and it was real open and burned pretty hot. I dialed back to 32ish and it sounded a little cold or closed to dynamics. I settled on 38 ma for now, seems to be where all of the tubes I have tried end up. I have used matched quads of JJ, Winged C, Ruby, and the original set of unmatched Ruby's. So far JJ's were dark and blanketed in tone. Winged C's sounded real organic and open with lots of creamy tone. The ruby's, both matched and unmatched sounded sharp but slightly open, especially when the bias was turned up passed 35ma or so. I liked the Ruby's when the bias was set towards the 38ma point. Gets me to the slightly creamy and dynamic range but still retains the crisp edge and chug that a 6L6GC is supposed to provide. Now somebody stop me from buying power tubes so I can afford a gallon or two of gasoline!