Your "battery" is not a real pure source of electrons
In fact most manufacturer use a battery with a DC/DC convertor *switching 1 million times a second) to get a exact voltage (5V usually) on the output no matter at what voltage the actual batteries are .
Problem is that all switchers (even your light switchers in the house) when turned on and off they make an "arc" rather a spark , that is very noisy (thats the reason most light bulbs will burn when you switch them on or off)
A quick link thats shows noise of some powerbanks
https://goughlui.com/2014/06/09/expo...vices-at-risk/
Please note that minimum noise is at 50mV but bandwidth is 10Mhz . Using the same bandwith on Shanti you get 10uV (1mV = 1000uV)
The noise on your powerbank is 50.000uV and noise of Shant is reduced 5000 time (compared with your present solution). Will the sound improve 5k times ? Absolutely not .
However:
Shanti will be a definite upgrade and you will hear improved sound quality since the second you plug it in .