If you just read that, and you’re asking yourself what high-impedance headphones are, then just skip this whole post, it won’t be relevant to you.
If, however, you saw that and thought “Wait, what?” then please read on.
Apparently, Apple have built in a high-quality DAC and headphone amplifier into the latest MacBook Pro (14-inch, 2021) and MacBook Pro (16-inch, 2021) laptops.
The headphone port on these laptops will automatically detect the impedance of attached headphones, and adjust the output to match. High-impedance headphones usually sound better than low-impedance headphones, but they require more power to drive them at a similar sound level. If the port detects a pair of cans attached with an impedance of higher than 150Ω, then it will boost the voltage on the output to allow these headphones to operate at a higher volume.
Apple are also utilising a high-quality, high-resolution DAC that can run at up to 96KHz (standard audio is usually 44.1 kHz, for example) in conjunction with the built-in headphone amp, so in many cases this may eliminate the requirement to use a separate USB-attached DAC/Amp.
Now, checking my older M1 Mac mini, it appears that the DAC on this unit can also handle 96KHz audio, but it can’t drive my Drop x Sennheiser HD6XX headphones, which are 300Ω impedance, to the same volume levels.