I coudn't care less about it has the same or simillar firmware. I don't have 901 and just 901 IEM card. The thing is, the firmware on 650 get crashed several times whilst playing several of my flac files and get rebooted. Not to touted about battery drain.. I have 603 before and although it is simple, it does work without hiccup. Oh.. and it used standard charger by the way.