I'm back again, just put valve art 6550a's in my newest acquisition and I'm biasing according to procedure listed on the amp. I bias one side to 72 millivolts (reads 72.4) and between k1 and k2 to precisely 0 mv(and it's exact too). My question is the balance control. If I run it down to zero +/- .01 it has bad sounding farting distortion (I think it's what they call crossover distortion, at least compared to the YouTube videos) but if I run it to where either side at idle is near 0 on the meter and peaks during playing at 2.5 millivolts between k1 and k2 it sounds huge. I tried doing the method on the amp, 25v output into 4 ohms and 40hz. Same thing. Sounds much stronger moving much more air to the points stated above. Am I an idiot or is this normal? I know a little about working on tube amps, I've done it before, but this seems out of normal range and wrong. If it is, then why does it sound better out of range?