It’s aimed strictly at audiophiles. The extra jack is a 4.4mm jack that’s more common in things like DACs.
An example:
https://nobleaudio.com/products/dac-amp-with-4-4mm-pentaconn-output
Pair a phone like this with a pair of Sennheiser’s and a bunch of FLAC files and you might have a really good time.
Oh so the jacks are different? Ok then. I thought the other sizes are dead or only used in niche $100k+ equipment