My recommendation would be to listen to the streamer for at least 3-4 days to get to know its sonic signature. Then switch to your computer as streamer. Spend another 3-4 days if the differences aren’t immediately obvious. Make a playlist specifically for this comparison. Make notes of what you hear.
If you must use a switch to go between the computer and the streamer, still avoid quickly switching back and forth. Go thru the entire song with computer then the same song in its entirety with the streamer. But…in my opinion using the usb switch can impair the sound quality and you will end up making a mistake…potentially…
FWIW, In every comparison in my system, my mac mini could not match the performance of a dedicated streamer. I used Auralic Aries G1 and Lumin U1 Mini for the comparison (USB cable was Audience AU24se+).