As far as longevity goes, my second pair has at least 700 hrs on them. My original pair has around 300 hrs, as far as I can recall. I haven’t swapped tubes in months.
I’m still very pleased with these. I’m listening to Shpongle/ Tales of the Inexpressible via Qobuz as I type this. Great detail,huge soundstage, and the toes are tapping!
Ray