Why so many tubes?

V8 is faster than V6 and V12 vaster than V8

Because its fun to spend big bucks on nos tubes.

unless you are the legendary Roger Modjeski ( RIP ) with oh so magical RM-10

what about preamps specifically? except for heat, the more the merrier?

mine is a tube tuner/preamp, 17 tubes in all

http://www.mcintoshcompendium.com/Compendium%20Docs/Tuner%20-%20Pre-Amps/PDFs/MX110LATE.pdf

Power from an amplifier is dependent on three things: the gain of the input signal, the voltage at the output, and the power dissipation of the output devices. The more output devices there are (tubes or transistors) means the more power can be dissipated without them burning up. So if you want a tube amp that can deliver 40, 50 or a 100 watts of power, you need more tubes. And more tubes means more parts and labor and that drives up the cost. 

Too many tubes? That reminds me....
https://youtu.be/H6_eqxh-Qok?t=35   

Which tube do you have in mind to remove?  

Atma Sphere amps don't have an output transformer in the path....its pure tube driving the speaker.

Good answer Ralph.

If direct path is preferred in the speaker by most, why the acceptance of a glass army in one's amp/preamp?

Not sure what is meant by 'direct path'... But if you need a lot of power, you might need a lot of tubes to make that power. If so, they'll be in parallel, which means the signal is fed to all of them and they all work in tandem to make that power. In that particular case, the signal path complexity is the same whether one power tube is used or 20.


We have a good number of power tubes in our amps because the power tubes, which are triodes, don't make a lot of power. But those amps only have one gain stage in the entire amp! That's about as direct as you can get.

You should check out the "parts count" of  typical, common, or high end solid state equipment and you'll have your answer.