Nuprime IDA-16 Owner's Questions

Two questions:

1. The manual instructs one not to use a power cable other than the supplied one. Is anyone using an "aftermarket" cable, any seem to work well..?
2. What high rez sources are folks using? Streamers, CD Players, etc?
3. Anyone made a firmware update? Is there a USB port/SD card slot on the back for this?

Thank you..!