Yes a linear power supply is a definite plus. I have a Lumiin U1 Mini and with the external power supply, it is a great product for streaming. May upgrade at some point later but for now but very happy with the Lumin. Nice sound stage, good depth and width. Good micro detail especially on the hi res stuff. Using Qobuz as the source.
Point of diminishing returns for a Network Streamers?
You have super cheap Pi streamers (build yourself), $399 IfI Zen, $500 Bluesound Node (no DSD), $700+ Pro-Ject Stream box, then $1k -$2k for Lumins, and others.
I'm running an old iMac as my Roon Core and running a super long, active USB cable to my Dac. I probably do not have to pay much for any improvement since my setup is not ideal.
I'm really fascinated by the Pro-Ject stream box...however...would it be a major improvement over the IFI Zen? I need DSD so the NODE is out of the question .
I could save and go with the new Lumin U2 mini, however....would it be a huge jump over the Pro-Ject?