any suggestions on what to replace Bluesound Node 2i with

I have a node 2i with the PD Creative dc power supply board upgrade.  Feeding it with an LKS power supply and upgraded dc cable.  Soft silver spdf (Nimak) cable to LKS Mh-da004 dac.  Also audio quest Vodka Ethernet cables through Etherregen.  Pretty pleased with result.  

I bought an Raspberry Pi 4 w/ HAT (allo digione signature). It has two separate power supplies, with a linear power supply for the output board and a switch mode for the raspberry pi board. 
Then I run coax tommy Schiit BiFrost 2. 
I cannot compare against anything beside a MacBook but I think it sounds stellar. 
I run Volumio which can be glitchy

this is sounding like a node aftermarket power supply cars and coffee morning

In general 2 channel systems sounds better than home theater systems, especially for the same price. Have you looked into adding a new pre amp instead? Or a pre and a dac?

I just got my Pi2AES working. Very pleased, its kinda awesome.

So I have a` Raspberry Pi with a Pi2AES hat on it. It feeds my DAC a very low noise and low jitter signal which lets it sing a bit better.
Before I had a regular USB connection to the DAC and it was pretty nice, its a Denafrips Ares II. Now its getting denoised by the Ethernet connection to the Pi, and reclocked by the extremely capable clocks in the Pi2AES. Then it goes SPIDIF on nice Cardas digital cable, to the DAC. If it was a more expensive DAC the Pi2AES would really come into its own. It speaks AES directly to any DAC and that’s another layer of goodness.

It just takes files from my computer, to the Pi, then to my DAC. Its very simple and what I want, but the Pi could do any damn thing. It does wireless and has 4 USB ports apart from the Ethernet port. You could stream from it, to it, use it to deal with all kinds of audio schemes, and it can directly deliver an outstanding bit stream to any device.