Switching to battery power

For those who are looking at a no cost option, this unit seems to be a favorite. I still wonder how different it would be from the above mentioned Milwaukee MX.

http://www.enjoythemusic.com/superioraudio/equipment/0218/Stromtank_S2500_Battery_Power_Review.htm

@goofyfoot 

"There was no difference in the resulting sound quality when the Stromtank S2500 was powering my front-end versus the Goal Zero Yeti 400. None."
GOAL ZERO YETI 400 LITHIUM PORTABLE POWER STATION – REVIEW BY ENJOY THE MUSIC.COM - Headphone Guru

George, I find this post odd.

I can understand if the logic circuit for the input switching get low voltage, it could send it into random switching between inputs.
But it's the heatsink creaking popping noises, that’s much more worrying, because the correct bias is all important for the amps safety.
Anyway like I said 1st post, it’s not a good idea to have "varying battery voltage" powering unregulated sections in the audio chain, as they are adjust to a certain voltage for optimum performance, and that is 99% of the poweramp section of integrateds, like this one probably.

Cheers George

pauly, why would the Goal Zero be preferred to over the Milwaukee?