I have good news for this topic:
Because of sound in kodi via hifiberry wasn’t working, I decided to use max2play only in the other rooms and in the living room I installed stand alone kodi on raspberry (without max2play). The last days I started reinstalling my max2play-raspi with the new max2play version (v2.51).
Originally I wanted to test another thing (HDMI CEC) and for that I pluged a raspberry with newest max2play version in my TV. Surprisingly sound via hifiberry in kodi works out of the box. I actually haven’t made a decision, but maybe I will again install max2play on my raspberry in the living room to listen to music and watch videos via kodi.