Q: Can I play my iPod and charge it at the same time. I’ve been advised that doing this is unsafe but I don’t believe it. Can you advise me please?
A: Absolutely. There is no reason whatsoever that you cannot both charge your iPod and listen to it at the same time, and in fact most car adapters and iPod speakers work on this very same principle—power is provided via the Dock Connector while also playing audio from the iPod. Further, it does not matter whether you are listening via the Dock Connector or headphone port.
When the iPod is connected to an external power source, it basically runs from external power and simultaneously charges the battery. When the battery is fully charged, the charging circuit shuts down and the iPod itself simply continues to run from the external power source. The only impact to listening to your iPod while charging it is that it will obviously charge more slowly since some of the power that would normally be used to charge the battery must be diverted to power the iPod itself.
The only other issue you may have is listening to your iPod while it is docked with your computer. In this case, if your iPod is connected to your computer, either because it is syncing or you have disk mode enabled, you will simply not be able to access any of the iPod functions, and therefore not be able to listen to it. Even in this case, however, as long as you are using automatic sync and not using disc mode, you can listen to your iPod once it has finished syncing.