USB powered Pro-Ject Pre Box S2 Digital question

Hi, I’m using RoPieee on two RPi’s powered by the RPi PoE HAT with the Pro-Ject Pre Box S2 Digital powered via USB only.
When I stop playing, the Pre Box S2 Digital remains powered, but after some time the Pre Box S2 Digital powers down.

Is this due to a setting in RoPieee, in the RPi or in the Pre Box S2 Digital?

Btw, I have the fan of the PoE HATs disabled and the RPi’s run at about 58°C idle and up to 65°C when playing music.