How To Measure "Current" In An Amplifier?

HELP!
I was following this thread, I thought, pretty well.
But, Damping factor came into play.
I read a Wikipedia page explaining it, and it sounded like a high damping factor allowed an amp to control a speaker cone better than a low one.
So, what makes having a high damping factor bad?
Sorry if this is something obvious...
Bob

Erik, I wasn't quoting you saying High DF was bad, only referring to Almarg's response that a high DF would wreak havoc on tube amps.
Though if you could elaborate why, I would appreciate it.
Thanks for your replies, but I am still a bit confused.
Ohms, watts, and voltage, I get, but this Damping factor still kind of eludes me.