Linlai 6SN7

Just checked my Psvane CV181 tubes in front positions (warm) and TJ Full Music 6SN7s (slightly warmer) in rear positions in my Cary SLP-98 preamp. Can hold my fingers on both, neither are "hot" or burn fingers.  Put my tongue on them, no issue there either - just kidding, yak yak 🤪.   Power transformer is separate/external on mine, and not heating up the whole preamp top plate surface area either.  It's going to vary by design with each preamp, transformer locations, and casing, venting too.      

OP, others,

Do you have your own simple tube testers? I cannot imagine owning tube equipment without one.

simple, seller seems to know what he is talking about

another

I have this one

they make a slightly larger model 257, still very portable

there are a lot of good ones listed now

people say: " this little one agrees with my other testers". that's always been true for mine as well. I've got a big calibrated one around here somewhere, they always agree, I don't bother with it any more.

As a general rule, preamp tubes don’t run anywhere as hot as amplifier output tubes and that’s one big reason they can last 2000-10000 hours. I’m currently running a couple of Amperex 6922 and while I wouldn’t want to be holding one, they’re not so hot as to Immediately blister my fingers.

All the best.

JD