OLED is used becouse TFT looks like shit. We are trying to use VA panel next year. Firmware is only for XMOS now. But we are doing microcontroller upgrade and CPLD upgrade for future products. It's not trivial stuff.My D70 behaves equally as the D90 when it comes to device control and behavior. Unfortunately, display burns are inevitable on these devices. For sure I will never again buy a device whose display cannot be turned off completely. Also have the D50s and it behaves as it should considering it also has the OLED screen. I really like Topping devices for their sound quality, own a bunch of them, but they still haven't stopped messing around with good options, features and ideas, aftermarket values, and in some cases they are even removing useful features in newer or refreshed devices (e.g. A50->A50s). I really doubt it could be "fixed" with a firmware upgrade. They're probably counting on us to change devices in the foreseeable future anyway .
Also what feature is removed from A50s?