Cleeds, I just follow frequent facts about Ref series.
It doesn't look like tube(s) problem. It looks like functionality problem.
bifwynne, you've mentioned bad bias resistor which may go with bad tube didn't you?
OP mentioned that tubes are less than three months old... What does it tell?
Just count facts and science becomes simple math.
Go with more facts throughout Audiogon posts about Ref series reliability: frequent premature tube blowing, bias resistor, bias DC cap etc... All these combined dictate sending unit to repair facility and back to get ripped off just like Ferrari owners do.
It doesn't look like tube(s) problem. It looks like functionality problem.
bifwynne, you've mentioned bad bias resistor which may go with bad tube didn't you?
OP mentioned that tubes are less than three months old... What does it tell?
Just count facts and science becomes simple math.
Go with more facts throughout Audiogon posts about Ref series reliability: frequent premature tube blowing, bias resistor, bias DC cap etc... All these combined dictate sending unit to repair facility and back to get ripped off just like Ferrari owners do.