The difference may be down to "Apple Dongle" in the era of USB-C/Lightning connectors and no 3.5mm - I know that despite not having particularly high impedance

The difference may be down to "Apple Dongle" in the era of USB-C/Lightning connectors and no 3.5mm - I know that despite not having particularly high impedance headphones, the difference was huge - and I specifically avoided "listening to equipment" and didn't invest too much into it.