Optimize my MacBook pro

How is the noise out of the power supply?  Try playing while it is on and off it.  If you notice a difference you may want to switch to a linear supply.

Also, disks are so much faster and cheaper now. It won't really help your playback, but you may have a better experience and a lot more space. :)

Your Briscati M1 DAC (if you still have it) is asynchronous, hence timing on the computer side makes no difference.   I would try to reduce injected electrical noise, by using USB cable without +5V and GND wires and possibly use USB isolator.  You could also try quieter, perhaps linear, power supply for your Macbook.  All computers have many internal switching regulators, but I believe the main power supply affect it the most (highest power).

Yes, I have my M1. When I use my MacBook Pro for music playback I always run it on battery power/ never plugged in. I did try a USB isolator but for reasons unknown to me I could not get it to work so I returned it. I could not get any sound output. 
As far as disks, I presume you are referring to a hard drive. My MacBook Pro has an ssd drive. I actually swapped out the original ssd and now have 1 TB of storage. Original was a meager 128 GB. 
I am on the verge of seriously considering a dedicated music server with a linear power supply but I’m not convinced that it’s worth it