Tsushima1, why get so wound up over a tube change from 120's to 150's? Ive heard the ref150 and it is a stunning amplifier out of the box. There is also some serious time involved in life testing. You see, you cant just test 1 set of tubes in 1 amplifier, you must test a multitude of tubes under various real world conditions, voltage variations and speaker loads. ARC must also see how the tube acts in a given circuit when mis-biased. It would probably surprise you how many people don't bias properly or frequently. If you want to try the kt150's, cowboy up and buy 2 quads and drop them in your amp. If they sound great then you have your answer, if they blow a resistor or two and you have to take your amp in for repair, then you would also have your answer. At the end of the day though, we would all be outraged if ARC said "sure, try them" and they cause a problem. There would be a thread started here on Audiogon slamming ARC for shoddy testing procedures.
In due time, Im 100% positive ARC will green light the 150 for use in their current product line, just be patient.
In due time, Im 100% positive ARC will green light the 150 for use in their current product line, just be patient.