Hi Foster,
Nice work, mate! Elegant, even, difficult to achieve with so much complexity, but you've done it.
Basically anything goes with this design if you can ensure it is hum free.
All wires to and from the level control are highly susceptible to hum intrusion from nearby AC lines, and thus your resolve to keep them well apart is essential. If in this guise the GK1-R has no hum, then all is well, but if it does, some further layout jiggery pokery might be necessary.
This component will take around a week of activation and use before it delivers its best. Lots of caps to bed in......
Cheers,
Hugh