How to connect mac mini to a DAC and monitor

Hi all,
I trying to connect my Audio Research DAC 8 to mac mini using USB
cable and HDMI cable to Samsung monitor.When I go to system preference and click on sound I do not see Audio Research in select a
device for sound output, instead internal speakers and S27B550 HDMI,
that is the model of my monitor.Please let me know what i am doing wrong. How do you connect your mac mini to your DAC and monitor?
I thank you all for you time and advice concerning this matter.

Hello , I have a little bit of input bit no definite answer . I just bought a mini a few weeks ago and hooked it up . I am using a Tranquility dac and Tranquility usb cable. My dac shows up . I did nothing to make it show up . Yours not showing up is a mystery . Audio Reseach is the place to get your answer . Maybe it is the usb cable ? One thing i need to do is manually choose between the hdmi and dac . I needed to shut off the sounds from hdmi . That was self explanetary .Again I would call AR .
I have had had good results by making sure the device and USB cable are connected and on when the Mac Mini is booted up. It seems that it doesn't always see something connected after it is running.
Try to go into application: utility folder then click on audio midi. then select device.