its likely the loading is internal in the unit itself.
And that we'll never know, as it is the graph shows roll off starting at 100hz already and that's with a 100k!!! loading, Stereophile usually also give a 600ohm loading, strangely omitted this time.
Would be nice if someone that has one and can do the measurement, to see what happens with a 10k loading as many Class-D's have.
So to those going direct with this make sure your amps input impedance is >100k other wise as the bass "could" be anemic as ozzy found out a few posts back.
Cheers George