Pretty simple stuff. Just buy an iPhone lightning dock ($39.00) from Apple or wherever and plug it in using a mini to rca cable (you can buy one very cheap - under $10 on Amazon) into any open input on your electronics. And of course, plug in the power cord.
The DAC is inside the iPhone. And is sounds great as other audiophile friends have witnessed themselves. Plus the phone is always charged.
I did a similar thing at a high end dealer in Boston once and he told me i was depressing him, given how good it sounded....no joke!
Here's a product link: https://www.apple.com/shop/product/MGRM2AM/A/iphone-lightning-dock-white
If like me, you have older Apple devices with 30 pin connectors, you can find new but discontinued Apple Universal Docks on eBay, which include a remote to boot. I have 5 of them for systems all around the house.
Would not live without any of these....highly recommended!