The capacitors in the box increase the power supply capacitance, presumably to increase dynamics and the general ease of the amp.
Capacitors do not induce hum in the circuit so the only reason that I can see for moving them into a seperate box is because they physically would not fit into the chassis. Understand, this is not a re-engineering of Nelson Pass circuit, it just increases the energy storage capacity of the power supply.
I would be interested in seeing the interior of the amp to see if there were any circuit changes or upgrades done on the boards. Once people get to fiddleing they tend to keep going.
Capacitors do not induce hum in the circuit so the only reason that I can see for moving them into a seperate box is because they physically would not fit into the chassis. Understand, this is not a re-engineering of Nelson Pass circuit, it just increases the energy storage capacity of the power supply.
I would be interested in seeing the interior of the amp to see if there were any circuit changes or upgrades done on the boards. Once people get to fiddleing they tend to keep going.