Apple has also improved an output on the new MacBook Pro that was actually thought to be dead, since it has not been found on iPhones for a long time: the 3.5 mm jack output. However, on the latest MacBook Pro model, this port has learned a few new tricks.
DAC with 96 kHz sampling frequency
So, while the port no longer offers an optical output like previous examples, Apple claims that the internal DAC (that is, the analog-to-digital converter) is so good that you can feed the analog signal right into your stereo. In addition, the DAC supports up to 96 kHz sampling frequency. This is called High Resolution Audio in audio circles.
Support for high-impedance headphones
There is also an interesting new feature for headphone users: headphones come with different impedances, i.e. resistances when driven by the signal voltage. The audio output in the MacBook Pro now recognizes which impedance the model used has and adjusts the output voltage accordingly:
When you connect headphones with an impedance of less than 150 ohms, the headphone jack provides up to 1.25 volts RMS. For headphones with an impedance of 150 to 1k ohms, the headphone jack delivers 3 volts RMS. This may remove the need for an external headphone amplifier.
This should be very convenient especially for professional audio users, since you can save an external DAC when traveling. Also for users at home, who like to use the MacBook as an audio source for the stereo system, the good promised audio qualities should be an advantage.
If you want to know about the corresponding settings in macOS, have a look here.
While the beefier output amp is certainly new, high-res (e.g. > 48 kHz) sample rate support is not. The DACs of older Macs support this as well. The models up to 2015 even sported a combined TRRS/Mini-TOSLINK audio jack, meaning you could connect an external DAC via optical cable. (IIRC, these models even supported 192 kHz.)
Oliver, you are right with the older models: I checked my MacBook Pro 2015 (connected via Toslink) and yes, it goes up to 192 kHz. Great for remembering us that also older MacBooks are still very capable!
Edit: Another fact: the MacBooks from 2016 on lost their ability to give out material with 96 kHz via the headphone jack. So this re-introduction still is kind of a change.
Thank you,
Stephan