first, some have asked how stax measured their amps. this is it going WAY back
https://www.ebay.com/itm/Sound-Tech...542214?hash=item3fc005c106:g:eVAAAOSwWLBaPAz8
i'm sure they don't use this anymore, as neither they or anyone else can keep them working. 100+ opamps etc.
For a while after that they were using the panasonic 7000 thing. Both of these things are 100% analog and measure thd completely differently than the ap, and they generate significantly different numbers.
lets start with the +350v power supply and the 50k plate resistor. You now add the 100k resistor to ground, and that +350 power supply
instantly is now 233v. But the -350 power supply is still -350. The entire amplifier is now completely out of balance. It just can't work correctly
under these conditions. It was never designed to work correctly into anything but a pure capacitve load.
do the same thing with the solid state constant current source, and nothing changes. So while the 100k additional load is unintended, it still
causes little issue.
the issue with the koss is the same thing. The koss uses a regulated switchmode power supply that monitors total power consumption.
the 100k resistive load causes the amp to consume much more power, and when that happens the power supply shuts down.