#1
Can someone explain how this works?

Here is the manual:

http://www.americanmusical.com/ItemFiles/Manual/Fender65DeluxeReverbManual.pdf

It makes it seem that if you use an external speaker, then the amp will not put out its max power.
MARTY FRIEDMAN--"It’s a lot easier to be technical than it is stylized; it really is... But I think it’s a lot more rare to have someone who’s really got their own sound because that’s something you can’t practice."