I am not aware of anyone manufacturing KT150 tubes other than Tung Sol. As far as tubes not inproving/settling in with some burn in, is not what my ears tell me. Just sayin.
New tubes...far more power??
I replaced my quad set of KT150's in my tube mono blocks a few days ago...replaced with a new set of KT150's that were quad balanced and now for some reason the power output is considerably more. So much so that i need to drop the volume control on my preamp by three notches! Plus, the sound quality is actually no better than before...and maybe even a little strident! Anyone have any idea as to why this would be?