If the output impedance of the amp is very high (like 2 or 3 Ohms), then you certainly need to add this into the simulation as it can have quite an effect of the speaker Q. Unfortunately it can also have an effect on the characteristics of the crossover network as well.
The high Z-out is one reason why zero-feedback valve amplifiers can sound very different from low Z-out transistor amps. (OK, I know there are other reasons as well, but the high Z-out is often the dominant one).
The high Z-out is one reason why zero-feedback valve amplifiers can sound very different from low Z-out transistor amps. (OK, I know there are other reasons as well, but the high Z-out is often the dominant one).