I'm not calling for regulation on audiophile gear. The only certification I'd require would be that the device will not electrocute you, and won't produce volume above, say, 140 dB, if sold by a company.
Consequences of any output from audiophile gear are normally not that serious. For a pregnancy test, it could be literally life and death: say, a murder from jealosy, or a suicide from guilt. This makes a strong case for regulation of what can have words "pregnancy test" and synonyms.
I'm fine with people being able to buy stuff that can kill them, be it a gun, a rope, or a substance. But I stand for clear and enforced labeling of such things, regulated proper packaging that prevents accidents, and other such measures that make sure the consumer has plenty of warning, and acts by deliberate choice.
With substances, it's much harder to assess if the thing in hand can kill you, than with a shotgun or a scythe.