What is an Impulse Response?
 It is a snapshot of sound, in this case, is a sound register of a mic on guitar cabinet. You need an impulse response loader after your amp, load any .wav IR file and you are good to go!

Which cabinet, speaker, microphone do you use on that?
All the cabinets pack and tone variations is based on combination of a lot mics, speakers and a lot of eq. Try to use your ear and find the best tone for your mix. All of them was refined a lot to be ready to mix or combined to another tone variation to achieve great results without use to much eq.