Here is good review of the Gamma amps from Phil McKnight:

https://www.youtube.com/watch?v=zEXJeIlewNg

All solid state *analog* is now a selling point!

The amp seems OK though they should have added a reverb (which probably wouldn't have increased the cost too much).

If you want to increase the gain, add a 10 uF cap in parallel to the Jfet source resistor.  If you do this, then your diode clippers may work better.