Since such a large number of the amps we talk about on here are 6L6 based, how about a 6L6 101 FYI? Using 6L6's vs. 5881's in the same amp? What do 6L6's do really well that EL34's don't? What do 6L6's not do well, that EL34's do better? NOS 6L6's vs. New Production 6L6's? Are there any current production American Made 6L6's? Are Groove Tube 6L6's worth the extra cost? Best Bang for the Buck 6L6's?