Looking for docking station with hi-rez digital output.

Hi folks, I found that i have older iPhone leftovers and wonder if i can still use them as dedicated WiFi streamers (such as youtube) and players with few hi-rez albums in limited 16 or 32g space on them. I plan to use several of my 4s and 5s with different albums saved and keep them as storage as well. I'm looking for descent performer that can accommodate both multi-pin and lightning ends with perhaps multiple docks. Professional (pro-audio) options are also welcomed. I also wonder if I can just plug in my iPhones directly to DAC. Is there any specific app to use to make it happen? What will be the advantage or disadvantage over the docking station digital output?

My beloved family upgraded their phones shortly after me g5 to g7. After this rapid upgrade of nearly 6 phones, Not only I realized that they worth fnothing, but remaining ones to pay-off dropped their used price also to a substantially lower than I owe for all of them. This situation indeed made me bitsy fangry.