Amp Simulators

https://www.guitarworld.com/gear/guitar-amp-simulators-better-real-amps

http://www.philoking.com/2016/01/28/the-history-and-future-of-amp-modeling/

https://www.reidys.com/blog/modelling-amps-what-are-they-and-how-do-they-compare-to-valve-amps-1071/