The F6 is a very interesting amplifier, first designed in 2012 and presented in October at the Burning Amp Festival in San Francisco. The transcript of my presentation there is available on the First Watt website under articles.

The amplifier was not initially slated for commercial production, and I continued to refine the design over the course of the next year and a half, working with different parts and adjustment values until both I and my listeners were satisfied that I had gotten the most out of this topology.

I think you will find that both pieces contain some interesting observations about sound and design.