So I’m guessing you replaced all the tubes? If so maybe try to put the preamp tubes all back in hopefully in the same spots. Is this a tube rectified version? As far as saying you set the bias where you liked it before, are you taking into account that the new tubes could be different (it obviously seems they are although it might be the pre’s) or are you setting them to about 70% of max dissipation? I mean if you’re just setting them to the same negative milliamps as the last tubes, that’s probably not going to be right for this amp, although we should rule out the preamp tubes first because just one shaky preamp tube can ruin the whole mix. Do you still have the old tubes right? and you did like it? Just figured it was time or whatever? That’s cool but we shouldn’t write them off quite yet.