Giving up on Itunes! Alternatives? I want to run my hardrive with a dedicated tablet.

After having my archives completely disorganized by itunes once again i’m throwing in the towel. I want to know everything about setting up a Tablet as a player for my digital music on a remote hard drive so i can do it right the first time.
I want a simple player (not Itunes) that can handle all file types, I have everything from mp3’s to lossless cd rips, over a thousand albums, not looking to spend alot of money, I work on my own equipment.
Lots of newbie questions! Why a dac? is there any real benefit or is this just a way to get people to spend more money. seems like this is more for av equipment? Cables? What are the benefits in terms of fidelity, should i be using usb to run my system? I’m currently running my digital through .999 silver minijack to rca and it definitely picks up noise from a computer or phone power cord and case. Seems like a lot of newer digital equipment gets signals pretty dirty, but i don’t know anything about it.
What kind of tablet, any fidelity drawbacks as far as this goes? I use Macs but don’t care if It’s an Ipad or whatever, just want the best sound, least interference. Does the material of the cables connecting the tablet to the hardrive or dac have an effect on sound?My system; It’s a pretty crazy set up of whatever I could get my hands on, predominately set up for vinyl but I have a huge collection of rare albums on digital and would like to begin archiving from vinyl. I’m running a Dynaco St70 (tube) through a dynaco pat5 (ss), JBL’s, all plugs are rca, solid silver interconnects, no shielding, ferrite beads.
The sonic qualities that are important to me are imaging and range, don’t want to sacrifice the extreme highs and lows to rule out a little emf interference, my amp is ancient anyway. You know, the vinyl sound. Please give me all the help and advice you can, brutal honesty preffered! There are just too many opinions and too much unhelpful information out there to wade through, just want to get started with something simple that sounds good. Not into expensive toys just listening to great sounding music!