For anyone coming across this topic in the future, here are some photos to compare the original Elektron PSUs with the non-Elektron branded PSUs of the original manufacturers (+Delta) mentioned:
They solely differ in the cable and the 2.1mm plug out of the PSU (an adapter to 2.5mm helps)
1 PSU-3b
2 PSU-3
!
3 Delta PSU
Other than the PSU-3c, all are dead silent — I tested these three PSUs with the Analog Four MKI, Analog Heat MKII, Digitone, and Digitakt. All working well, had them on for a few hours.
The Delta PSU is smaller, yet delivers 4A, and the built quality seems fairly well. Costs were 3€ for this one.
Cost-efficient alternatives.