I can’t speak directly to the Goal Zero 500 but the 1500 really opened my ears to realizing how much my wall power was effecting the sound. I tried the 1500 on just my front end and it was ear opening to say the least. Out of curiosity I also tried my power amp with the 1500 and the loud inverter fan kicked in after two or so minutes, lol. Even with the amp not being compatible, I knew I wanted to hear everything off grid which led me to where I am today.
OP, I’m guessing you and others here have experienced the ups and downs of our systems sounding great one day/night and then brittle and thin on another. After going the battery route, the consistency of my system isn’t something I think about anymore because it sounds great no matter when I use it. I now understand that the demands on our power grid at different parts of the day can seriously effect the quality of our sound. I won’t presume to know all the technical reasons for this, I know because I’ve tried it.
For reference, this is my gear: YG Acoustics Carmel speakers, Pass Labs X250.8 power amp, Pass Labs XP-22 linestage, Luxman EQ-500 phono stage, George Merrill Signature Polytable, REL S/510 sub, Border Patrol DAC/Bluesound Node for digital. These all plug into a Puritan 156 and then into a Giandel 5000W pure sine wave inverter and Lossigy 400ah Lifepo4 battery. Not once in almost two years of running this setup has the inverter fan kicked on.
The site below is where I got a lot of useful information, it’s not my exact power setup but it’s close.
http://tweakaudio.com/EVS-2/Inverter_Power.html
I know my particular battery setup isn’t exactly what you’re asking about but I wanted to put his out there for people interested in the topic. No matter what you decide to do or try, good luck to you!