Hi I don't have Nagra VPA's, but I do have a Nagra PLL and VPS. They do heavily test their tubes and warranty them. Not all 845's also are perfectly to the same specs and could possibly cause a issue. Those are GREAT amps, I've heard them lot's at my dealers...I spend the $$'s....it's not a racket.
I agree it's a little pricey...but you also don't have to worry a about a bad tube and matching is important in balanced amps...like you VPA's
Out of curiosity, what preamp are you using with them?
I agree it's a little pricey...but you also don't have to worry a about a bad tube and matching is important in balanced amps...like you VPA's
Out of curiosity, what preamp are you using with them?