Are you using the USB or the optical output of the MacBook? I use the optical output of an iMac for a substantial part of my listening, going wirelessly to a Gen 3 Apple TV and Simaudio 300D DAC in my main system and directly to a Simaudio 100D DAC in my office. Of all the changes I've made in wires, tubes, etc., by far the greatest improvement to the sound in both systems came from putting a Wyred4Sound Remedy reclocker ahead of each DAC. In particular, the improvement in the office system was much greater than any amp or speaker switch I'd made.
I got the reclockers because of numerous references I'd seen to the high jitter from the Apple devices. And my experience bears out the importance of that. The change was considerably more dramatic in the office system using the Simaudio 100D than in the main system with the Simaudio 300D. I'm assuming that's because the more expensive 300D does a better job of handling the jitter on its own.
No experience using USB so my experience may not apply in your situation.
I got the reclockers because of numerous references I'd seen to the high jitter from the Apple devices. And my experience bears out the importance of that. The change was considerably more dramatic in the office system using the Simaudio 100D than in the main system with the Simaudio 300D. I'm assuming that's because the more expensive 300D does a better job of handling the jitter on its own.
No experience using USB so my experience may not apply in your situation.