Is it safe to charge/power other USB devices with the cube adapter that came with the iPhone? I just want to plug in my little voice recorder during meetings instead of having to replace the batteries alot. The manual for my voice recorder says it can be powered through the usb port, and lists some recommended adapters. I googled the adapters and I think they have the same specs as the apple cube charger. Just don't want to fry a $60 recorder!