The MCU is no soldering. It's a simple ic that is about 1/4 x 1.25" in size. Maybe 40pins and simply pull the one out of the back of the displays pcb board. Note the key on one side.
I am NOT sure if the dac19 needs MCU or not. Just be sure to ask.. Especially if you have 7sec display go dark option.
I needed it for my nfb28, and lost the feature as I had no idea I was even getting an MCU let alone was supposed to custom order it with 7sec display go dark. Kingwa is kindly sending me a new MCU to fix the issue. But I wanted to let others know to ask about MCU if you upgrade any of your audio-Gd product with amanero
This photo sort of shows the MCU
At least part of it. This is from my nfb28. Again, I don't know if the dac19 needs MCU replacement too. Please ask when you order!!