What we have learned so far about modeling: 3 simple rules

 So, here is how i understand it:

There a 3 stages:

1) Pre amp

2) Power Amp

3) Cab and Mic

1) Pre amp is the first and easiest thing to emulate. Indeed there are also simple analogic pedals that mimic the functioning of valve preamp with nice results. What make the diffrence in the preamp stage are gain stages and EQ stack.

2) Power Amp: a valve power amp works in a way that you can get output and headroom 3 times than  solid state amps. So you should compare a 20w solid state with a 5w valve, a 50w solid state with a 15w valve, a 100w solid state with a 30watt valve. In the same way, to get the push of a 100w valve you will need 300w of solid state power, and so on. This make comparisions a bit more difficult. So, set your expectations to one third of the nominal power.

3) Cab and Mic or impulse response. The result of this element of the equation is a powerful eq filtert. Cab and Mic (or IR) are a core stage in crafiting your tone.