Youtube loses the ability to produce sound at pretty much this too, I’d say. To be sure, try sinegen.
Edit: Also, “theoretical” is 20hz. But with sinegen at 15hz or even less (slider goes to 15, but type “10” in “hz”, press “enter”, then click “power”) and your headphones will rumble. 10 hertz, so, 10 times per second. And if you can’t hear it, you’ll feel it (if your headphones can do it).
Obviously, lower your volume on your amp before trying anything. Hearing damage is permanent.