probably they dont like adding usb dac to dx90
it is very simple...they would kill all own DACs they are selling now
why to buy extra dac when you buy DX90 and it has monstrous dac already...
it would probably kill mamba from market and everything similiar
i wouldnt be surprised if even when they add usb dac functionality there will be some limits or wanted disfunctionalities or quality drops...otherwise they could delete all other products and just sell DX90
it would be a perfect all in one
Do you really think they care as long as they sell one of their own somethings? If you think it will render some of their own products obsolete, consider other makers as well. In your scenario, if it actually worked as you say, iBasso still sells a device and many many more of them over other makers product as well. Making many many more also reduces per unit price and gives higher profits. It would be a very welcome situation for iBasso. Yours is a narrow view.