Wanting to learn just a bit more, I asked Liu via his global reseller Alvin. "The P7 uses the most streamlined circuit because a linestage is responsible for amplifying the source signal where the stability of each component and bias point is key. Adding gain to a line-level signal is a very sensitive affair so we set the operating point of the gain stage to pure Class A bias. The circuit architecture comprises a Jfet input buffer, the volume control and the gain stage all with independently regulated power supplies. To achieve high dynamic range, we use ±50V DC power rails throughout. The gain factor is x 3 with single-stage RC lead negative feedback. I also designed for the shortest signal path. I wanted my gain modules swappable for testing, tuning, stringent channel matching and possible future upgrades so we socket rather than solder them into the PCB. The new gain switch on the rear panel cuts signal strength by 4dB."
In established Kinki fashion, the two power transformer encase in aluminium bunkers.
Here is one of the critical gain modules parked on the metal remote.
Each module is preceded by a blue trim pot to fine-tine the bias current. Note the beefy gold-plated trace areas.
Quality filter caps…
… and precision voltage regulators…
… make up some of the other parts.