Schiit setup troubleshooting

I have 2 Aegir amps set up in monoblock configuration. The Schiit Freya S serves as my pre-amp. My source is a Lumin U1 Mini, connected via optical to a Chord Qutest DAC. The Qutest is connected to the Freya via single-ended connections, and the Freya is connected to the 2 Aegir amps via XLR. So, single-ended input into the Freya, then balanced output to the Aegir amps - this setup is not producing any audio. I have confirmed that there is a signal traveling to the Freya from the DAC. As recommended by Schiit, I am using the NEXUS modes on the Freya pre-amp (i.e. active modes, which should convert the single-ended signal to balanced), to no avail. Any thoughts on what might be causing this?