I see no reason why crosstalk should be a problem with the ipad’s mic / headset input with a correctly built cable: DIY iPhone line input / headphone cable
It certainly isn’t for me! The only real problem with this input when using Cubasis, is the fact that Steinberg in there infinite wisdom, did not use ‘Measurement Mode’ (ios sdk since 5.1) for the audio input… Which causes a steep high pass filter to be engaged… Therefore ruining the bass frequency response!