my experience has been terrible with with this brand. In fact the only returns I got for over 2 years (with probably over 250 6SN7 pairs sold for other components during this time) both came from this preamp.
In two years you replaced the tubes in two Freyas. This is what is relevant, not other models.
Terrible?
Given the rather unpredictable nature of tubes sometimes, varying from very reliable and operationally stable to being dead on arrival and everything in between, a tentative intuitive statistical consideration would suggest that your experience with Freyas is well within the bounds of acceptable.
More data - including tube failure for Freya, actual user experience using tubes with Freya, brand of tube, type (new or NOS or used) etc would be required for a more robust conclusion, but terrible I think would not be one that I would suggest based on those numbers.
Should I be incorrect and a systemic issue be found that suggests a design flaw, then again, I would reiterate that Schiit really needs to hear about these things. Their authorized dealers may have this responsibility - and it is in their own commercial interests to report them.
For those people with email, drop Schiit a note on their help and support portal. And they do supply a 5 year warranty on the amp.
Off topic - what is really surprising to me is that no other 6SN7s have failed during this two year period. That in itself is quite remarkable given your large sample size. I know 6SN7s are very good, but that is quite an endorsement.
