And yes, you can use all the fancy apps on your source device like DAP, laptop or Mobile phone and then connect M30 via USB
After experimenting so much in the past I really have to say M30 sounds to me great either using the internal apps or just the standard players like Audirvana, Amazon, Apple Music etc from your source.
It has enough rabbit hole options playing around with the locally configurable amplifier modes and upsampling options imho without diving even deeper into the likes of UApp, Neutron etc