Just to put another data point on here.TLDR - I am running with a fairly exotic combo, but the 14" M1 MacbookPro (2022) is definitely limited.
FYI, my DAC is the chord MOJO, running at 768kHz (I know, just because it can, I'm not sure the frequency makes that much difference, at least not to my ears), and my headphones are Focal Stellia's.
The difference is very clearly there in all frequencies but most notably in full-range music where the top-end tends to lose definition and the bass becomes boxy as the signal chain run out of "budget".
I would personally always upgrade the analog bit first (your headphones/IEM's), but once you've reached the limit there, then a decent DAC is great. Mine is relatively portable and can work with my [cheap Android] phone too where the need is much greater.