Thread drift from my own post but; I ended up buying from Tyler and Chelsea of TCtubes.
This is what Tyler had to say about the KT150;
I have a long history of buying tubes from Kevin Deal of Upscale with mostly good but not universally good results.
Bringing this back to ARC, one of the few times that I DID get a response from ARC was when I wrote them inquiring if it was possible to use 6550s, KT88's or KT90's in my Ref150SE. I mentioned that my Devore dealer thought that those tubes were a better match for my Devore O/93's. I received a very curt response that my dealer (they knew his identity because I referenced him my name in my inquiry) "was an idiot" (verbatim) and that I "would be foolish to listen to him" and that there was no conceivable reason to use any tube other than the KT150 in my amp.
This is what Tyler had to say about the KT150;
I avoid most QC issues by paying extra for tubes tested and matched by New Sensor. This costs me more on the front end but I don't get the rejects that they screen out. I don't rely on their matching. I order batches all from the most desirable range of tubes for the type I'm interested in. They are supposed to send me all closely matched tubes in the quantity I've ordered. I then retest those tubes and match them into sets using my own methods. In the end, I run the tube sets under the operating conditions they will be seeing in the amplifier that the customer has. In your case, most ARC amps run around 420-430v plate and screen and draw about 65mA per tube. I set the tubes up under these conditions and verify that they are matched at those voltages before shipping.I have Jim McShane's post but won't repeat what he had to say for fear that he would prefer that I keep it private. Having just re-read it, he did say that he plans to revisit the KT150 at a later time in hopes that the QC has improved.\
If I see problems with tubes as I go through this process I simply return them. This pattern is time intensive and cumbersome, but I don't get hardly any returns on power tubes as a result.
Most tube resellers will buy the tubes in larger quantities and in untested condition. They will end up with a range from about 70% of expected values to over 200% of expected values. I will not play that game anymore. Too many rejects for the factory to take back. Paying them for screening on the front end saves me time and hassle in the end. My customers get tubes screened three times (once by New Sensor, once in my initial tests on the AT1000 testers, and finally in a matching fixture at actual operating voltages for end user's application) and much better matched than otherwise possible.
Tyler
I have a long history of buying tubes from Kevin Deal of Upscale with mostly good but not universally good results.
Bringing this back to ARC, one of the few times that I DID get a response from ARC was when I wrote them inquiring if it was possible to use 6550s, KT88's or KT90's in my Ref150SE. I mentioned that my Devore dealer thought that those tubes were a better match for my Devore O/93's. I received a very curt response that my dealer (they knew his identity because I referenced him my name in my inquiry) "was an idiot" (verbatim) and that I "would be foolish to listen to him" and that there was no conceivable reason to use any tube other than the KT150 in my amp.