First Streamer...

I²S, is an electrical serial bus interface standard used for connecting digital audio devices together. It is used to communicate PCM audio data between integrated circuits in an electronic device. Wikipedia

Protocol: Serial

Designed: 1986; 36 years ago

Width: 1 data line (SD) +; 2 clock lines (SCK, WS)

Data signal: Push-Pull

The newest Bluesound Node (130) is a pretty great streamer to start with. It's easy to use, the software is terrific, and it's easy to set up. At $600 it's easy on the budget, and can be very very good with a good DAC. I am not familiar with the Saturn, but it looks to have USB co-ax digital inputs.....so it's a start. If you outgrow the unit at some time, you can probably sell the unit and get a chunk of your money back out of it.

Moon Neo Mind over on USaudiomart for $750.  Also a Bryston BDP3 over there as well.  Bryston BDP on here for around $700 and they sound great.  Bryston interface is  a bit spartan but their units sound good and work as Roon endpoints as well 

+8 for Bluesound Node. It's a no brainer at $600. App works with Android. I use the app on iPhone and it's great. 

I put an aftermarket power supply in my Node 2i.  They range 150 to about 500.  I installed it and I  am not a technician.  I used Pd Creative.  Teddy Pardo is another brand.  It is a nice sound improvement.