Double yup on the KT120's. I switch back to the Psvane KT88's every now and then just to exercise them, but it's just not the same. +1 on the 55mA also. Another thing I notice is that I have to tweak the bias fairly regularly on the Psvane's where the KT120's are rock steady.
Your comment on rolling is appreciated, but it's very difficult if not impossible for some of us to hold off. At least I'm at the point where everything I've got is broken in. I've even settled (more or less) on my favorites.
I did make one last tweak of the week ... I swear! ... Been running the KT120's with a Mullard GZ37, 1940's RCA foil getter 12AU7's on the channels, and an RCA clear top in the middle. The tweak? I've got three of the clear tops and switched to one of the spares for the middle.
wOw ... BIG difference. So, moral of the story ... even identical tubes can have differences, so if you got extras, try them. I liked what I was hearing before, but this one made for some serious improvements.
PS ... your source for the Chinese tubes could very well be the problem. I received several stern warnings when looking at amps to be very sure and use factory authorized sellers. Apparently a lot of seconds floating about, and even rumors of street kids taking over the factories on the graveyard to slam out some clones. You could get lucky, but anything goes wrong, your chances for support or remediation are slim to none.