Can I use Spotify Connect AND Mopidy Addons on the same Hassio RPi at the same time?

I have a Hassio installation on a RPi 3 B+. Connected to the RPi is a Nuforce USB DAC. I installed the Spotify Connect addon and that works like a charm. But, I would ALSO like to be able to play local mp3s and use TTS through the same USB DAC output. However, it turns out that I can only have Spotify Connect OR Mopidy activated since they both seem to block the sound card from the other addon. Is there a way I can have both addons activated?

Example warning log message from mopidy when Spotify is activated: “WARNING GStreamer warning: gst-resource-error-quark: Failed to connect: Connection refused (1)”

Optionally: Can I obtain the feature I want in some other way? (That is, use Spotify Connect, play local mp3s and TTS with output from the Hassio Rpi USB DAC.)