You missed several possible steps, revisit what leg of your power panel all the digital stuff is on…
electrical sleeve heatshrink
I used a MacBook (with solid state drive) for a number of years. I would always unplug and run on battery power to play music. I was using an +$10K DAC. I will admit I never tried an isolation method.. cones, platform, or any of the other stuff I had laying around because it just wasn’t of high enough sound quality to expect to hear the improvement.
After nearly twenty years of experimenting with digital streaming I concluded the only way to good sound is through a purpose built streamer. PCs and laptops are a cornucopia of electro magnetic fields, vibrations, and conflicting CPU services. If this is a fun exercise for the fun of figuring out if you can hear a difference, have fun. My money is on you not being able to hear a difference if you put it on a mount made for an electron microscope (which my turntable is on, and I can hear a difference). If you are seriously looking for better sound, buy a dedicated streamer. Blue Sound sells a very popular budget one.
I had a Mac laptop as server.
I ran an Audioquest Jitterbug and iFi USB Silencer in parallel.
Had Black Ravioli Pads underneath. Used a Halide Bridge USB to coaxial reclocker. Drove that with an Aqvox USB power supply. Was going to use some fo.Q damping tape, but have changed to a streamer.