New KT150 tubes?

Has anyone any experience with these pretty new tubes. There are already one or 2 amps I know of, that use them. The review of one of these amps in a UK magazine suggested they were a little warmer and more natural sounding than the nearly new KT120's

The article also suggested they were a straight swap for KT120 based amps, with no adjustment necessary. They are more than twice the cost of KT120's, but still not too costly compared with NOS tubes. I know changing from KT88's or 90's to 120's. did require some amp modification. I have an ARC reference 75 and might want to try the new tubes at some point, ARC don't seem to have a customer E-mail service, to ask the question
Xumbug and Joe ... I don't think I'm contradicting the comments and caveats posted above by saying that even if the Ref 210 "seems" to work ok, how can one know for sure whether using the KT-150s will, or will not, prematurely age the amp over the long term. To me 100+ hours is not "the long term."

Maybe it won't hurt the amp, but I surmise that Xumbug dropped some major bucks to buy his Ref 210. Unless he has DEEP pockets and doesn't care, my advice is wait until ARC approves the KT-150s for his Ref 210.

I sure as sh*t, I am not dropping those pups into my Ref 150 until ARC gives the green light. So, I'm taking my own advice.
I sure as sh*t, I am not dropping those pups into my Ref 150 until ARC gives the green light. So, I'm taking my own advice.
It's your amp and you can do whatever you want. There are players and spectators ... what makes the world turn.
I am going to call Kalvin at ARC and ask him about the use of the KT150 in my Ref 110. I suspect that they haven't nor will they test it in the older generation Ref amps (unless there is sufficient demand/enquiry on the part of owners to do so)but will push them to see if I can get a definitive answer. I will also ask about current Ref amps and if I get an answer will report back.

Separately, if the answer definitively comes back as no for my specific question of dropping the KT150 into my Ref 110, does anyone here have a view as to whether the Winged 6550C SED tube is preferable to the KT120 tubes in the Ref 110? It seems like of all the 6550 variants, the Winged SED version is the top dog and often goes for big bucks but wasn't sure if anyone here has compared it, either to ARC standard issue 6550s or to the KT120?

Would appreciate any input on this front. Thanks.
As an ageing cynic, really ARC have no interest in showing the 150's will work in the current Reference power amps. They have the reputation of bringing out new models faster than a Milan fashion house. I would put money on them having a range of Reference power products, using the 150's, within a year or so.
" Step this way Sir for the new super reference Power amp, the 120's are so last year"

An unworthy thought I know.
Cmalak -- I haven't tried the KT150 in my Octave V110 but I have tried the SED 6550 and the KT120. Both have very similar sonic signatures. When I was looking for SED EL34's a few years ago (had the Octave V70se then)I met with Jim McShane and he told me about the quality of SED tube taking a nose dive. He said that Arc was the largest customer for SED tubes. In fact when I got my V70 the SED 6550 was the stock tube with the SED KT88 as an option. The KT88 is a much warmer sounding tube.