Point of diminishing returns for a Network Streamers?

If you are using usb to any dac, you will have inferior sq.

what is a streamer? A computer running a proprietary OS usually running on hardware with gimmick technology to promote a higher price.

Keep any server out of your audio room and use a better interface to the dac than usb. 
Why would anybody think a pi is a better server than say a Mac mini? You think it’s because of Linux? Think again. Every 3rd party streamer uses some version of linux, some with tainted OS’s because the vendor thinks they have a tweak that performs miracles, I would never run a tainted linux because if anything happens to the streamer or the company goes out of business, who will support this linux version? Good luck

"The Lumin alone is a significant upgrade over the iFi Zen..."

"If you are using usb to any dac, you will have inferior sq...."

ahhhh yes... anonymous keyboard bravado at its finest, gotta love it...

grains of salt, many grains of salt recommended...

I've had good results moving from a Raspberry Pi4 to a Sonore Optical Rendu streamer feeding a Chord Cutest Dac.

I then moved from the Macbook Pro to an Antipodes server as the Roon core, this was a significant improvement as well.

My thoughts on priority 

1. Noise is the enemy -  do every thing tiy can to prevent it

2.  Are you happy with the software interface?  

3. connectivity to other devices

4. Price

My Choice was to purchase an all in one solution  Auralic Altair G series streamer/DAC.