Some DACs have a master volume control interface which is not connected to the listener-controllable volume control. In some cases, that master volume control can be automatically attenuated by as much as 70% when the DAC detects connection a Linux source like Aurender.
If you experience very low volume output from your DAC when connected to your Aurender, please try using the "Reset DAC Volume" command in the Conductor app found under Settings>Advanced>External DAC Volume Control Correction:
In case this does not solve the problem, contact Aurender technical support by sending a Remote Support email request. In some cases manual adjustment is necessary. This can be performed by Aurender's software team remotely.