@harpo75, no doubt you're right. Although one can get JJs and the superior Tung-Sol 6SN7s (whose price has more than doubled in six months), it's a struggle finding NOS or Electro Harmonix (now PSVane). I have been sent dud tubes from two different dealers. Replacements take forever and are never matched. So yeah, I'm giving the new plugs a try & will report any findings of interest.