my two tungsol 6SN7GTB, are driven by two CV4014 (thank you Datum Walnut!) and... they sound really fine but... the two tubes seems to have (well, I think they have) a quite different operating temperature, I swipped the tubes between the two position and the hotter one is always the same (tube, not position), I've done the same with the CV4014 (thinking could be from differences in those but no, the hotter 6SN7 remain unchanged)...here is a picture, what do you think about? all normal or one of the tubes is fault?