@potterma perhaps you are onto something here in regards to the mechanical connection of the resistors. The losses we are experiencing may in fact be due to the leads of the resistors themselves. I may have a possible solution for that. Can you or someone else using the resistor network snip off the leads close as possible to resistor and solder on a 20awg solid core fly lead and see if listening impressions improve? Most resistor leads are quite thin and we may be running into a limiting/loss effect due to that. I would do it myself, but I only have the HE-adapter box and I really don't feel like hacking it up right now lol.
The signal runs through wire and pcb traces inside the amp. For those with stock wiring, it also goes through a mini-coax terminal at the cup which isn't even a bonded connection. An inch of resistor lead isn't going to make a difference.
Here you go... http://www.troelsgravesen.dk/graphite.htm