Thanks for your reply. I am not an engineer but did take physics 301 and I understand much of what my subsequent (much) research garnered. I hope this may benefit others…I have used Tube Depot before but got the last 2 GE 6072A from Brent Jesse, a well known tube Guru.
He states that at least 48 hours of burn-in is necessary for a tube, especially if it is NOS, as the gas and resultant deposits need to settle, having to due with emmisivity…even resultant vacuum inside the tube.
I think most laymen confuse “burn in” with “warm up”…
Also, interesting enough, I spoke with David Geren at Cinemag transformers, whose company designs and builds audiophile transformers. I have 1 each channel in the mic pre mod. He (and his audiophile clients) have found that also with transformers there is an easily perceived aural difference after burning in a transformer with white noise signal, especially those with higher turn ratios and impedance.
Brent Jesse states that, unlike transformer burn in with a signal, tubes just need the “heat” to change the chemical structures inside the tube.
I hope this helps. I have found that there are very different two sides to this subject…radically opposed. I prefer to research and then trust my ears to the results. I am doing A/B experiment with sound recordings…If you’re interested in the results, let me know…
Disclaimer: I have questioned the above named for years in pursuit of their products and found them superior, but I am …just a picky end user. I neither am employed by them, nor a representative of them.