Source: Me, playing in amateur orchestras for twenty-plus years.
Sidenote: I find the sound of an orchestra tuning to be a deep joy! All those instruments sliding into place is just delightful
As a regular orquestral concert goer (I would say I average a concert a week per year at least) reading your description of the tuning process gave me goosebumps.
It really is one of the best sounds on the world! The tension! The anticipation! And then seeing and hearing a well rehearsed group of people move from casual conversation mode into serious business mode in a few seconds. And from chaos comes order. And then the silence, only broken by the applause when the maestro and soloist(s) arrive.
One of life's biggest pleasures if I may say so.
It seems like the story is usually told about an "Indian musician" and something similar happened in reverse at a Ravi Shankar concert, where the Western audience applauded after he tuned.
I love it as well. But at the same time it makes me feel like an idiot because all I can think about is the PS3 menu sound when you power it on...[0]
And A is a ery triumphal note when everyone converges on it.