Hello!
I made a cheaper hack just a few days ago...
And here are the pics of the modification of the Dnano charger:
Works really nicely and don't destroy the Dnano charger.
I use a simple regulated universal voltage adapter.
This one can get output voltage from 1.5 to 12V. with 1000mA at 12V (1400 at 6V).
It also contain different plugs.
And I can use both of the power sources. Cells or Adapter.