For what it's worth, I dropped ARC supplied KT 120s in my Ref 110 and can say with assurance that they provide noticeably more power, dimensionality and transparency. The caveat is that I did this bit of listening with a temporary pre (in place since I sold my Ref 5) as I await Ref 40 to be delivered next week. The pre is by a small manufacturer who I would rather not name until I have concluded my listening with the Ref 40. I am confident that not more than a handful of Agoners own this pre.
In any event, there is a stridency in the lower treble upper mids that I did not hear before, possibly because my 6550s , with less transparency, did not reveal as a preamp or source (cd) problem.I suspect it is not the fault of the new tubes. I will report back after Ref 40 break-in which may take some time.
If it works out as I believe it will, I will be able to wholeheartedly recommend the kt 120s.
