Do we still need 6550 or KT88 tubes?


I would like to learn your opinion and experience with KT120 tubes.

Considering that KT120 match 6550 or KT88 based amp (is a direct replacement), how do you like the sound of KT120?
Do we still need 6550 or KT88 tubes?
Do we still need to pay for NOS power tubes?

BTW at the moment a KT150 tube is announced. Should be even better than KT120 and could be interesting upgrade for current KT120 owners.
milimetr
"With oil prices so low and strangling the Russian economy, our response ( like the response if Jimmy Carter in 1980) may be to impose an embargo if Russia gets more agressive in Ukraine."

Putin and his henchmen are the one's strangling the Russian economy with their blatant corruption and criminal activities, low oil prices are just exacerbating the problem for his people created by HIM. Agree, buy now before the inevitable embargo by this or the next administration and his response, doubling down. There is no palatable solution with that guy, he is just too ambitious and dangerous.
I remember observing the shear terror in Yeltsin's face as he was endorsing him as his predecessor. I think the announcement was to Yeltsin and not the other way round.
On German Radio I heard Merkel, who is one smart woman, refer to Mr. P as delusional.
I recently replaced the KT 120's in my ARC REF-75 with the KT-150's. Night and day! Highly recommended for this amp.