Well yes. That's what I think the Vorbis dude showed. We can try it. We would have to agree on what represents worst case and typical ultrasonic levels and frequencies.
Some, if not most, amps do not filter input ultrasonics coming from DACs. Proly not even the mighty Hoe-2.
(making crap up because I'm only wikipedia smart about this...)
Maybe something like 1000 Hz, 82000 Hz and 85500Hz
produce a 3.5kHz blippityboo, see if that interacts with the 1kHz tone to make something at 2.5 kHz.
or whatever values work to create spikes that won't overlap with the natural harmonics of the test tones, or even the first order of imd products