Yeks Guide to the Fractal Audio Amp Models
Forum member Yek (Alexander van Engelen) describes all Amp models in his Guide to the Fractal Audio Amp models (PDF).
The guide was preceded by a series of threads by Yek on Fractal Audio's user forum. Forum member Simviz assembled the contents of the threads into a PDF guide. Yek updates the PDF guide periodically.
Brief information about the Amp models, derived from the forum threads and PDF guide, is available here.
If you find the guide useful, consider donating to a good cause as explained in the guide.