I plugged in my new digital to analog converter in my ps4. When I plugged in earbuds, or use a speaker, i can't adjust the volume, it is SO loud. My monitor has NO sound this is why I bought. please assist
The optical output is fixed so you could get a DAC with it's own volume control.
You could connect a passive audio volume control to the output of the DAC you have.
You could use powered speakers with their own volume control.