Hlep chosing a streamer/server for my DAC

Greetings Audiogoners, I took the dive into digital last year. I bought a Gustard A26 and loved the sound it produced. Close enough for me to analog—I currently have an Audio Research VSi75, a Herron Audio pre-amp and a VPI table.

I have been streaming through my MAC laptop. I know, not optimal. I want to make the next move to a dedicated streamer where I can sit in my chair with my tablet and drift off into sonic bliss. My problem: I'm unclear as to which streamer to pursue. Can you guys demystify things for me; dumb it down for this vinyl guy to understand? I just want to ensure that I'm able to stream the highest possible audio resolution between my DAC (32BIT/768kHz PCM, DOP 256, Native DSD512) and my streamer. I also want to avoid compatibility issues with whatever connection I choose to use between the streamer and DAC.

For example I have read that some streamers will only stream at a certain resolutions despite the streamer and the DAC being capable of much higher. Is this really a problem to be concerned about? Also, which connection should I favor 
AES, SPDIF coaxial, TOSLINK, I2S or USB. I have been using USB but I find that I can only stream at 24/96 even though higher bitrate files are possible (probably the limitations of my MAC). I currently use CAT 6 Ethernet to my MAC and USB to my DAC.

My budget is around $3700 tops. Can you help make make the right decision? Some of the streaming choices I have considered are the Lumin U2 (used) or U2mini with an S Booster, Innuos Pulse (used) or Pulse mini with power supply, Roon clone with a linear power supply or an Eversolo DMP-A10.

I freely admit I know next to nothing about digital audio. I need just the basics to make a wise purchase. Any help you can offer would be greatly appreciated. Thanks.