That was from about 2% battery remaining. I did some testing on charging rates using a Power-Z KT001 USB Power Meter and an Anker PowerPort II PD (A2321 model number) to see what I would get. Tested with Power On & Off, Screen On & Off, and both Mango Mode & Android Mode. Here is a summary table of my results:
My conclusions from this:
1) Using USB A/QC (Anker PIQ) it doesn't make a difference if the screen is off or on and with the DX220 off the charge rate is slightly lower but then again there is no power consumption by the DX220.
2) With USB C/PD the DX220 charges at an appreciably higher rate when turned on and with the screen on it does even higher - most likely to counter the power used by the display. Slighty higher rate in Android Mode.
3) Since I spend most of my time in Mango Mode I decided to just charge from there with my DX220 on but not listening to any music.
4) If memory serves me correctly I got about 75% charge within the first hour.
Hope folks find this useful.
Like others have said - your mileage may vary...
Cheers,
Tim