Settings for Oppo bdp105 used with external DAC (Tambaqui)

I just bought a Tambaqui primarily for streaming and stored file playback using the USB input but thought I’d hook up the Coax digital out from the Oppo BDP105 for playing CDs. I understand that the Oppo will not output anything on the optical and spdif outs when playing SACDs (only HDMI) but I can’t seem to get any signal on the spdif when playing regular CDs. I messed with the audio settings some but haven’t found a combination that works. Any recommendations on how to make this combo work?

Thanks