I have just bought the D1. I notice the USB power as the power is not good enough. The problem is the bass is knd of weak.
I end up make an 1A 5V power supply. It make a big different.
I also find out if I rip the music to 32 bit non-compressed flac file is the best. I do compare with 24bit level 4 and 24bit level 0
However, I like the 32bit flac more though. I understand that the D1 is only 24bit.