I just sold my M3 to try a few other cheaper DACs. If I re-purchase it I will get it with the Ethernet input. When I talked to Bricasti requesting info on getting the Ethernet input added, they suggested it would sound better than the M5.
For now, I'm trying to decide to stick with a Pi based streamer or try a Lumin U1 Mini, Bricast M5, or maybe Sonore
opticalRendu to see how they compare. Neither of the cheaper DACs I've purchased support Ethernet and one supports MQA over USB so I really need a streamer that supports multiple outputs, or just switchover to USB as that seems to support the most decoding options generally speaking with all of the different DACs I've been looking at.
What is tempting is to try a new Pi4 with the DigiOne Signature spdif output board (
https://www.allo.com/sparky/digione-signature.html).
This board looks pretty impressive and requires two power supplies:
"
It needs 2 PSUs, one for 5V/2A-3A (RPI) and a second power 5V to 6V 100mA. We do recommend the cleanest power supply possible (batteries, linear but even a good SMPS will work)"
https://www.audiosciencereview.com/forum/index.php?threads/review-measurements-of-allo-digione-signature-and-diyinhk-pro3z.4660/ gave it a clean bill of health.
For ~$240 + power supplies you get what looks like a pretty impressive digital output. They also offer a USB based board too.
For AES, these folks offer a Pi based output board
http://www.pi2design.com/pi2aes.html.
So many things to try...