Lumin U1 vs Lumin U1 mini + sbooster?

Have you tried any other streamers like SOTM 200 ultra?

I guess for me, going from my gaming PC direct to my dac vs any kind of streamer would make more of a difference because a mac mini is likely inherently much less noisy than a gaming pc.
But interesting findings indeed.  Im actually not all that surprised by your findings with the sbooster. Looking under the hood it seems the u1 mini has a pretty solid isolated SMPS.

I am surprised by your findings. There is simply no way that a Mac Mini will outperform a dedicated steamer.  Something else must have been at work here

Surprising posts, agreed.  Dedicated streamers tend to win out from the old PITA computer setups.  Is what it is I guess.