I have something similar. One thing I do is keep the browser tabs to a minimum, especially on web sites that have a lot of video ads. These sites take up CPU cycles.
I also use a Sonare microRendu that isolates the computer noise from the DAC. It is an Ethernet-2-USB conversion device. I have learned recently that I can improve on this because there is some noise on the Ethernet wire that gets into the DAC. However, the microRendu sounds very good in my setup. There always the option of making an OPTICAL network from your computer to the DAC to lower or eliminate this Ethernet noise. Sonare also has a solution for this which they market as SystemOptique (a few hundred $$).
I also use a Sonare microRendu that isolates the computer noise from the DAC. It is an Ethernet-2-USB conversion device. I have learned recently that I can improve on this because there is some noise on the Ethernet wire that gets into the DAC. However, the microRendu sounds very good in my setup. There always the option of making an OPTICAL network from your computer to the DAC to lower or eliminate this Ethernet noise. Sonare also has a solution for this which they market as SystemOptique (a few hundred $$).