I’ve noticed some clear differences between 6SN7GTBs that both my pre and power amp currently use, and NOS GEs are my faves for those. I continue to use 12AX7s in my guitar amps (and previously in my Jolida 502p amp also, although I no longer own that amp). I did wind up using Gold Lion 12AX7s though, as they sound great, are consistent, and are readily available.