Portlandlay
I use to have an old Sennheiser headphone hooked up to my Iphone 7. Average sound. Since I travel a lot for work, I decided to take spend the money on a decent rig!
My new travelling set up is HIFIMAN 400S headphones, Dragon fly red, I phone 7 .
All my cd`s are burned in the AIFF format in my Iphone 7.
It does sound pretty good , to me I emphasize to me. And the rig is easy to travel with, which is a plus. DAC needs no power plug. It is strictly a traveling rig, but I do enjoy it very much. It is also highly recommended by TAS /STEREOPHILE magazines reviewers.
You can spend a lot more money for a better rig, but for me, spending about $ 550 gives me a sound I LIKE! Hope this helps.