The G01 / G02 and 501 / 502 seem to use the same boards and power supplies; all of them have linear power supplies with toroidal transformers.
The G01 has a built in tuner.

The 502 / G02 have an extra power supply pcb loaded with reservoir capacitors and looks to be a true dual mono design, I can imagine that even used in unbalanced system, the ‘02’ models would be a step above the ‘01’ models.

I had a 501 before I moved to a 568; even with an analogue source and analogue power amps and ‘speakers, the 568 was better than the 501.