I've had a good run with some edifiers (820 I think?) as spares and am looking at these among others. 48dB sounds hilariously high though - 24dB is what aviation headsets do passively and also IIRC basic certified ear muffs for industrial noise. Given that each three dB is a halving of noise, 24/3 = 8 so are they saying it's 1/256th of the noise coming through compared to my old David Clark headset? Doubt.
FWIW my Bose history includes 25s, 35s and 700s. They all do well in windy cars etc whereas the Edifiers often do not. And the Bose 700s can make people think I'm at home when I was actually driving at 110kph in an mx5 for hours. Beyond the basics, the real world noise rejection and microphone performance is more important than some impressive number, even if true. Oh and sound quality would be nice :-). Might give some a go.