You're already going beyond what you should. You're not an executive, you're not in the legal department to give promises or make proclamations on what the company directive should be.
@Blank Verse is out of his depth on this issue, and conversing with you, as if you're the one that should be telling people that you would replace their headphone for being fried, when warranty claims are usually handled by distributors (and in the case of particular events, the manufacturer works with the distributor for servicing and liaison between customers).
The idea that you (just am amplifier designer) should speak on behalf of the company is insane (unless you moved up in the executive circle of the company). But even then, you wouldn't be speaking on their behalf unless green-lit by the legal team.
Something like making a public statement of "we'll replace any headphone, and fix all defective units anyone has" is idiotic. I could be upset with my headphones currently as they may have channel imbalance, and go and damage them, claiming the Topping device did it. If such a public aforementioned statement was made, Topping would serve as an insurance company, more than an audio company with how many people would potentially be making claims about damaged headphones (if only to get a new one in case theirs isn't to their liking anymore).
Blank Verse, you're talking to the wrong person and speak from ignorance on how affairs of this kind are actually handled. Even if Topping sent users literal shocking devices - where do you imagine John here would be the person to talk to about internal company policies? Him speaking ever on their behalf is a move that could end with him losing his head in the company. So when he does illuminate of company policy as something evolves, take it as someone who here in the US would basically be in breach of NDA as norms are concerned. And as such, you, piling on him like this, doesn't make much sense.
What is it you actually want him, a designer of analogue devices for Topping, to actually himself do? It's not his company, so choose your word carefully.
EDIT: you say:
Show me what sort of moves other companies do, to where Topping is falling woefully short (or John here is as well). And as for you "imagining" this may be a complicated subject. There's good reason for such intuition. Listen to it.