Suggestions for Digital and Analog Connections?

USB gets bashed a lot by those selling competing products. A lot of work has gone into audiophile USB. A lot of $100K systems use USB. I am very happy with it (in my <$100k system). I did spend $200 on a nice USB cable from my Innous Zenith MK3 streamer to my Dave DAC.

Lots of good RCA cables out there. Audio Envy is an affordable one. I build my own with KLEI connectors and mundorf wire braided.

I don't know Apple but I assume the mini will be your Roon Core?  I recommend installing ROCK, always stable.  

Jerry

I did the comparison when I had an Auralic Aries G1 streamer between USB and AES/EBU and the USB sounded better. The cables were Audience AU24SE+ USB and Fadel AES/EBU. Definitely not apples to apples but take it for what it’s worth. 

I would recommend using an iFi SPDIF iPurifier with a coax connection before the coax input of your DAC.

As for brand of cables my personal preference would be Mapleshade

My budget preference would be Pangea.

USB vs Coax... Depends. Cable sensitive too.

You are advised to try whatever you can.

Start with cheap cables on both so you can A-B.

I did that on one setup and coax wire does way better SQ than Toslink glass. USB about tween.