I haven't been able to find my multimeter, so I cant confirm the Amp output, but per the graphics on the Amazon link I posted the output on both USB ports was change from 1amp and 2.1amp to 3.4amps.
So, take that as you will ¯\_(ツ)_/¯
It charges phones pretty quickly.
Here is a wall of text describing how I think our setups are similar. There is a TLDR bottom line, well...at the bottom.
So, I have two packs that have full lights and sound. One is a mad scientist project that shoves all kinds of stuff into a pack and is hardly applicable to this conversation, but the other is very similar to what you are putting together, though it does have its own weirdness to it;
It has a single usb cable that is the power input, ie what I connect the power bank to. That usb cable goes to a USB 3.1 splitter. Specifically this one:https://www.microcenter.com/product/485 ... ub---black
I specifically purchased a USB 3.1 hub because the amp output of .9amps per usb port (of course thats dependent on the input, but I wanted to make sure I had the capacity) and I wanted to be able to just plug stuff in.
I have the Arduino board plugged into one port for power and I have the soundboard wired to the Arduino board for power (I believe. Its been awhile since I have looked at that one) and then I have two USB speakers connected to two other ports in the hub. I followed CountDeMonet's plans almost exactly when wiring up all the lights, etc. to the gun and rest of the pack (except I left the resistors out of the bargraph, but thats another story). I used 2 USB powered speakers from Microcenter (I have the volume on each set at about 80-85% of max) for the sound. The pack isnt the loudest Ive ever heard, but it can be heard well enough at a con to be shown off, so its not bad:https://www.microcenter.com/product/485 ... -sound-bar
As I said everything is run from a single power bank. I have used the one I link above many times and it will run the pack on idle with hum for around 40 hours...In case you need to do that.
I have also used these el-cheapo power bank from microcenter (there is one close to me).https://www.microcenter.com/product/488 ... nk---black
It is a 2,600mah battery pack with a .8A output and it will run that pack for around 4.5 hours.
I dont know what kind of speakers you are using, so it might be an Amps issue, I dont know. However it is possible to run a pack with very satisfactory sound on a 1.2amp port (or less apparently).TLDR:
One issue that I DID have is that the 3.5mm did not make a good connection in the jack in the sound card, so the sound was super soft at first. I re-seated it a bit and rotated it and now its fine. That may be all that is wrong with yours as well.