Hi, sorry for the late response...
We ARE offering mods for the PS-1 and HC-1.
The mods for the PS-1 are $250 and include the following:
Upgraded op-amps.
Upgraded key input signal path resistors to Visahys.
Upgraded power supply filtering.
Upgraded power supply decoupling with Black Gate capacitors.
HC-1 Mods are $200 and include the following:
Install a single Bybee filter per channel at the transformer secondary voltages serving the dual mono circuits in the PS-1. This significantly cleans up the supply voltage to the PS-1 and lowers the noise floor.
Thanks
Dan W.