How about this one? Foldable USB Wall AC charger adapter for iphone 3G/iPod - eBay (item 330361432311 end time Oct-19-09 16:33:23 PDT)
It's supposed to use for the iPods. I'm not sure if it would work fine with the v2.
Well to start with the last question, when leaving it on it consumes more power then when switched off. Further there is no difference.
Either way (on or off) the batteries are charged independent of the switch position and go into dripple charge when they reach near max level.
As with V1 we have a very conservative charging philosophy getting max life out of the batteries. Negative point that it takes longer to reach a good full charge. hence we advise overnight charging.
Rgds and enjoy. Hans.
I have another question.
Can it play while fed by a wall charger?
Hmmm, my plan is to feed it by another USB DAC and in the mean time, charge it by the the wall charger through USB input.
However, when I do that, there's no sound coming out. And when I un-plug the wall charger, there's sound. Really have no idea about this.