Question for amp experts

Technically? No. 

Take your imaginary great sounding amp. Now imagine that amp inside a speaker. No way it will sound as good as outside away from all that speaker vibration. The speaker also will sound better with its crossover further from the power supply, etc, of the amp. 

Yes, it possible for them to sound even better.  The key word is synergy.  The amp can actually be matched to the driver.  Additionally, the crossover is easier to implement.  This applies to both analog and digital designs.  Although it is most common, the amp and crossover do not have to be placed within the loudspeaker cabinet.

Hi,
theoretically speaking if same amp used yes, but with a seperate one no. And still you will need a preamp. Vibration issues and interference with crossover can be minimized to a point with construction. I cannot imagine a tube amp inside a speaker cabinet.