Questions about Sharkoon PMP35

We have now clarified this for you. This combination works without any problems. As soon as you connect the microphone to the audio adapter, the voice goes through the microphone and the loudspeaker still goes through the mobile phone. If you also connect headphones to the audio adapter, the sound also goes through the headphones.

Normally yes, at least I was able to use it that way without any problem

The PMP35 comes with a 4-pin 3.5 mm TRRS type jack (with pin assignment CTIA according to the Sharkoon website). So it depends on whether the iPad is prepared for this plug and what it does with it. The normal stereo audio signal is taken from the PMP35 plug via the tip and first ring and output to the headphone output socket. The second output jack of the splitter brings the additional channel of the 4-pole jack (according to CTIA on the 4th ring), is clearly mono only and actually intended as a microphone input. I assume that the iPad also expects this situation and does not output audio on the mono channel.