Marc, ... short answer is no. Reason is ... I forgot. Haven't heard or read anything else about the KT-150 to date. I certainly would NOT drop this monster into my amp without an OK from ARC. As I am sure you know, ARC agonized about the KT-120 for some time before using it as a drop in on many of their older models. I gotta believe the same would be the case with the KT-150. I bet Gary-Hifigeek has more information about the KT-150 than most since he is an authorized ARC repair tech.
Btw, how are you luv'ing the Ref 150? Thinking about picking up a pre-owned unit if the price is right. I know there is a unit on the market now. The owner is asking more than I care to spend, especially since I am enjoying my VS-115.
FBO others: Just did a little tweak the other day. I decided to plug my Ref 5 SE and VS-115 directly into the wall sockets. I previously ran all of my gear through a surge protector that supposedly offered lightening protection too. Wow -- a no cost tweak that yielded a very noticeable improvement. I wonder what improvement I will hear when I run a couple of dedicated lines for my rig?? BUT ... I gotta remember to pull the equipment out of the wall if thunder storm.
BIF