How can i improve the sound of Iphone 11?

"Have you thought about iPhone 11 > Apple Lightning to USB > AQ Dragonfly?"

This is a good possibility. Getting a  (Apple Lightning to USB) is easy enough, and the Dragonfly isnt big, but i never heard it and wonder if it will sound as good as the DX90.

Or if another mini dac would do better. A quick google search for "best portable dacs" revealed different reviewer opionions. No one agrees which is best - Cobalt, Audiolab M-DAC nano,  Clarus CODA USB DACm,  THX Onyx,  Maktar Spectra X2, etc.

Had a Dragonfly black. Sounded fine, especially when out in the noisy world. Sold it after I got the Questyle QP2r and never did an a/b comparison. Considering getting a cobalt for my desktop, which can serve double duty…

I used a cypher labs 720 dac with my iPhone and it sounded very good. I also used it between my Mac and desktop speakers

I prefer my Chord Hugo 2 but when I'm traveling light I love my AudioQuest Dragonfly Cobalt.  It delivers amazing sound in such a convenient small size.  I bought an AudioQuest Dragonfly Red when I misplaced my Cobalt and was surprised that an even more affordable DAC can sound so good.  The Cobalt has a lower noise floor, generally sounds better and is smaller in size, but the Red is really all you will need if you will be mainly using it in environments where you may hear some of the background sound.  After listening to both of them side-by-side I can easily hear that the Cobalt is clearer, more precise, has tighter deeper bass and more natural extended highs, a greater sense of depth and width to the soundstage, and an overall more pleasing sound than the Red. It really is worth the extra $100.

I use an Apple Lightening to USB adapter from my iPhone to a Dragonfly Red to drive my Hifiman planar ‘phones and it improves the sound significantly over using the iPhone itself.  Specifically the soundstage expands and clarity and detail are greatly improved as well.  In short, it brings back all the audiophile goodies that make music more enjoyable.  I don’t think you’d be disappointed by the sound, and it’s easy to use on the go.  The Lightening to USB3 adapter is supposed to sound better and gives you the capability to charge your phone while listening, which is nice to have.  And the Cobalt might sound even better although I haven’t felt the itch to upgrade from the Red.  

One thing I’d recommend is trying Qobuz — I switched from Tidal and am much happier, and no MQA crap to deal with.  Anyway, hope this helps, and best of luck.