I spoke in person to a very highly placed ARC representative (whose name I promised not to reveal but all who follow ARC would know) in late 2014 just around the time that the Galileo series was in production and prior to the release of the SE amp versions (which the rep hinted would come soon). I asked if I could drop KT150s into my Ref 150. He said that ARC had tested the KT 150s for months in the standard models and that there would be no harm in dropping the KT150s into my amp although he also said that ARC had not obtained sufficient quantities of the tubes to sell them direct. He suggested that I wait for ARC to sell them in the future or, if I was in a hurry, to purchase from Upscale Audio.
I did so, biased the tubes at the standard 65mVs and am currently beyond 1,800 hours with nothing but satisfaction. Months later the SE series came out and, of course, contained modifications specifically designed to accommodate the KT150 tubes. Nevertheless, I understand from those who have compared the SE to non-SE amps with KT150s that the tubes alone get you most of the gains in sound that the SE provides in a combination of the KT150 tubes and hardware upgrades.
I am sure ARC would never officially say this now--after all they want to sell the SE versions--but look at the posts here on Audiogon and Audio Aficianado in late 2014 and early 2015 regarding the issue and you will see a number of non SE owners dropping KT150s into their Ref series amps. All came back with favorable results and no problems were reported.
I did so, biased the tubes at the standard 65mVs and am currently beyond 1,800 hours with nothing but satisfaction. Months later the SE series came out and, of course, contained modifications specifically designed to accommodate the KT150 tubes. Nevertheless, I understand from those who have compared the SE to non-SE amps with KT150s that the tubes alone get you most of the gains in sound that the SE provides in a combination of the KT150 tubes and hardware upgrades.
I am sure ARC would never officially say this now--after all they want to sell the SE versions--but look at the posts here on Audiogon and Audio Aficianado in late 2014 and early 2015 regarding the issue and you will see a number of non SE owners dropping KT150s into their Ref series amps. All came back with favorable results and no problems were reported.