The Photon Booster / Line Driver is an adaptation of the Seymour Duncan Pickup Booster (version 2, 2015, traced by Aion FX in 2019).
The V2 update of the Pickup Booster added a true class-A output stage. The first version was traced in 2007, but the new version had not yet been dissected by the DIY community.
The Pickup Booster is designed to provide 25dB of crystal-clean Class A boost. It also has a resonant peak switch that makes a single-coil pickup sound more like a vintage or high-output humbucker depending on the setting.
Because of the direct interaction with the pickups, it’s recommended to use the pedal as the first effect in the signal chain, otherwise the Resonance switch will not work as advertised and will just act as a slight treble cut.
The Photon is a direct clone of the Pickup Booster with no modifications other than some additional power supply filtering.