Hi Guys, thanks a lot for those informations 🙂 It is funny, that in son´s cheap keyboard from Amazon is everything ok. I am going to try another Apple cable without charging port ( even now I wasn´t charging and playing simultaneously ) and if this new cable won´t help I can try some of mentioned isolators. I don´t know what feature has Numa Compact 2 from first post ( YT video ) that you can see this keyboard like audio device, it is amazing. Both of Numa and Casio has MIDI IN/OUT and MIDI USB. But some app have this choice inbuild, like for exaple Synthesia, but I don´t like this app. You can choose audio input and output.