Cab Driver is a tube power amp and cabinet coupling simulator.
In this case the power amp of ENGL Powerball and ENGL 4x12 cab were used as a reference.
Put this plugin after a preamp or a power amp simulator but before a cabinet simulator e.g. any impulse response based convolver like Ignite Amps NadIR and other.
No difference will you put this plug after a preamp sim by alone or a preamp sim with power amp sim. The goal of this plugin is not to simulate a tube power amp, but to simulate coupling effect between a tube power amp and any cabinet.