Pretend your headphones only moved with 8-bit resolution. There is no possible way the experiment could derive a useful conclusion, but you might trick yourself into thinking it did. Especially if your sample size was 10,000 people.

More realistically, the participant might choose music for which no 24-bit recording exists.

It's very important to control for every variable. It's actually not possible to gather info about what headphones the listener is wearing. Even if it was, it wouldn't be possible to know whether they're doing the experiment in a quiet room, or whether there's a traffic jam just outside their apartment window, or whether their dog is barking during the test. Stuff like that.

Crowdsourcing this is an incredibly cool idea, but it'd just be so easy to believe you've performed a reliable test even though some variable undermined it.

I forgot another variable: Whether the music was recorded at 16-bit resolution. Most musicians use 24-bit, but it's easy to imagine that some of their samples might've been quantized to 16-bit without them realizing it.