Do all tubes glow


In my CDP the two 6922 tubes glow and the two E83CCS do not glow but are hot, and the unit seems to play fine. Thoughts?
jl35
In my CDP the 6922's glow brightly but 12AX7's emit very little light. Hey, do we have the same CDP?
Just looking at old threads. Looks like we do. The lack of glow worried me at first. Never saw a tube not glow