Battery-Powered Audio System Buzzing?

@sid-hoff-frenchman said;

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. 

(or rather through a Zero Surge unit)

Did you try that on the 120Vac output on the inverter?

 As I read the above quote, you were only using the battery/AC inverter to feed the audio system . Therein not using the wall outllet AC mains as well at the same time to feed other audio equipment. Therein two different power sources to feed audio equipment whose signal grounds are connected together by wire interconnects. Is that correct? 

If you were using both power sources, the chance of the two power sources AC sine-waves being in sync, in phase, with one another are slim to none.

As for grounding of the inverter... Did you read the instruction manual. What does it say about earth grounding the inverter? My guess it says to connect it to the electrical grounding system of the building/house.

If you were using both power systems, the inverter power and the wall AC mains power to feed equipment connected together by wire interconnects and the inverter was not grounded to the EGC, (equipment grounding conductor), at the same wall outlet I can see the inverter using the signal ground wire in the interconnect as a path to ground. That could possibly be the result of the buzzing you were hearing through the speakers.

But, if only the inverter was being used as the power source, and it was earth grounded, if that is what the inverter manual says. Well then ???

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And yes, originally when I posted I still had 2 subs and the DAC going through wall power. Once I put everything on the battery the buzz disappeared.

Thank you for sharing that tidbit.

As far as I remember these issues arise due to the generator neutral and the house neutral not being bonded to the same reference point setting up a neutral/ground differential which causes current flow through the ground...

Not really.... A standby generator is connected to the electrical service entrance neutral conductor. BUT, DO NOT TRY TO CONNECT THE HOT FROM THE GENERATOR DIRECTLY TO THE HOT OF THE UTILITY POWER. The Utility power system will win the battle. You can kiss the generator goodby and probably a lot of associated electrical equipment.  

It has nothing to do with the neutrals of the two power systems being bonded together. It has everything to do with the two AC power systems are not in sync with one one another, therein, in phase with each other..

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Interestingly the 2000-Watt sine-wave inverter I use will synchronize to mains frequency within a couple of cycles if mains is connected.

I assume the inverter circuitry uses a static switch that does not connect, parallel, the inverter to the AC mains power until the inverter AC sine wave is in sync with the AC mains sine wave.