I was not expecting the AirPlay2 to sound so close sonically to the microRendu.@yyzsantabarbara
If you are using USB from a microRendu into a USB DAC, the DAC is treating the data differently than through a network connection.
The technical reasons for this will make most people's eyes bleed but in a nutshell the protocol(s) being used to deliver the stream data are quite a bit different under the hood.
AirPlay2 and Roon endpoints are essentially "capturing" real-time playback occurring on an auxiliary device over the network.
In this scenario what you are comparing is the Matrix DAC's ability to "capture" an AirPlay2 stream from the network and deliver it directly to the DAC circuit, to the Sonore's ability to "capture" the same stream (assuming from AirPlay2, or Roon, it wasn't exactly clear) from the network and convert it to a USB digital stream for use by the USB input on the DAC.
Looking at it in this light you can see there is an additional process in the signal path using the Sonore microRendu which is unnecessary if Matrix audio have done their job correctly on the network side. It's likely why you are surprised at the similar fidelity.