It's slightly pricier than other adapters of similar size, but the sleeker CNC aluminum build, LED indicators, and loud amp output make it a quality purchase.
https://www.notebookcheck.net/Tiny-199-USD-THX-Onyx-DAC-USB-C-to-3-5-mm-adapter-supports-MQA-rendering-for-on-the-go-audiophiles.552755.0.html
EarMen Sparrow is better for the same price.
MQA has no benefits, only potential drawbacks
The M12 from Questyle sounds better and is cheaper.
The amp uses THX AAA topology, so if you like the Drop/THX AAA 789 headphone amp this uses the same principle in miniature. It's linearity is it's strength, great with good headphones but potentially less forgiving of your 128kbps MP3 collection.