Battery-Powered Audio System Buzzing?

I’ve seen many people proclaim the merits of powering one’s audio system with a battery, rather than from the wall AC power. I purchased an Anker SOLIX BP1000 battery as a household backup in case of power outages. I figured why not give it a shot on the audio system.

Well, it powers the system just fine, however, there is a buzzing that comes through the speakers when using the battery as the power source. When plugged directly into the wall (or rather through a Zero Surge unit), there is no buzz. It is silent as can be. 

Does anyone have any ideas as to why the buzz might be happening when powered by the battery? Any insights would be much appreciated! For reference, I am running a Macbook -> Schiit Yggdrasil OG ->Don Sachs preamp -> Schiit Tyr monoblocks -> Tekton Encore towers.