Volume suddenly dropped via my MacBook Pro

Help! I have a MacBook Pro in bought in 2016, using it with a Bricasti M1 DAC. While listening, the volume suddenly dramatically dropped. The rest of the system works fine, and volume is normal using the a CD through the M1. Thoughts on how to restore the normal volume level while using my MacBook Pro? I use J River media center. Thanks! 
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Just to add a bit, I can get some audio out, at nearly max volume on my pre-amp (Pass XP20), but it's distorted. 
If you believe the issue is with your Macbook Pro you might want to use the Apple online support center.  Ask "Why might my Macbook Pro suddenly lose volume?"  If that doesn't work give your local Genius Bar a shot.  I have had great outcomes with the "geniuses".  Good Luck!
Don’t know if it’s the MacBook Pro or not. In 2017 I lost all audio via USB and it turned out to be corrupted software in my M1. I did an SMC reset on my MacBook Pro- I’ll try it out later 
It’s not the MacBook Pro- using a different DAC, playback is without issue- 
@zavato,  Based on your above post, it seems the volume issue might be your Bricasti M1 DAC.   I suggest you call them on Monday to discuss your options.  See this link: