That is the same as a traditional amp meter works. Digital ammeter designs use a shunt resistor to produce a calibrated voltage proportional to the current flowing. You believe a meter but not when it is done outside of the case?
Adrian - you are not understanding my point. I understand the measuring of current using a shunt (something Rossi has done before). The issue is the power (either generated from or delivered to) the QX. That depends on the voltage across the QX -something Rossi seems unwilling to measure directly like any normal person.