Fractal Audio Systems
That's intentional. The JP amp has a fixed input gain control. The "Gain" control on the amp is actually an Overdrive control. If you use Authentic controls there is no Input Gain on "Gain".Well this model sounds super good!
A minor bug: resetting the new JP amp from the front panel and the input gain defaults to 5.70 IIRC. I haven't tested if this affects other amp models.