This product is awesome! Delivers clear and precise sound till your ears bleed...if you wish;-)
Besides- what I don't understand: The NX4 DSD is too small to get a good grip in handling with my Galaxy Note 8. Moreover battery capacity is rather low...and charging almost takes 4 hours. So: Topping should consider to build a device double the dimensions for better handling and integrating a big, fat battery!!! If they do so one time, I will buy again for sure!
Despite of that- great effort!