Spent many hours troubleshooting this exact scenario myself last night. I cannot tell you how to solve it because that will be dependent on what you’re using for the clean side power but I can tell you how I diagnosed it to get me on the path to solving it.
I bought the Digione Signature from Allo so it came with one “dirty” power supply which is for the dirty side. I had to supply my own clean supply. At time of order Allo will sell you a second supply for the clean side but this is against their recommendation. My understanding that the second supply they send, if you go the route of buying a 2nd supply, is the same as the dirty supply. So… to rule out a power issue on the clean side…
I took a very nice USB charger I have rated at very decent output and used this for the dirty side. I verified this powered the dirty side without issue (booted, stayed on network, no logs indicating an issue, etc.). Then I disconnected power and let everything settle for 30 seconds 9or so). Using the Allo “dirty” power supply I plugged this into the clean side of the board. I then took my USB charger and plugged that in on the dirty side. Glorious sound was heard by all!
If you’ve got the Allo power supply try it on the clean side. If not, keep trying different supplies. I think, ultimately for me, the solution was attaching a power supply that didn’t shut itself down when the Sig started drawing less power than it took to keep the power supply alive and active. A lot of chargers and power banks will shutdown when the load drops to a specific rate.