I found one piece of the puzzle. My idea to attach and de-attach the soundboard with plug connectors wasn't so good. The connectors are passing only 3A.
I took them out and have much less sound issues. I got it still on purple and white. THanks for the hint!!!
Then I took a look on the charge port and noticed that this one is only passing 5A. Are there ports letting more amps run through or how is this issue to solve? I need a place for my kill key and don't want to disassemble the saber all the time to load the battery :/.