In theory, the iPad can use the same 30-pin dock donnector to interface with any existing iPhone or iPod accessory, the practicality is that there’s simply no way you’re going to smash it into an existing speaker dock’s iPod port.
The Cerulean RX Stereo Bluetooth Receiver can help with that: it’s a simple wireless adapter that is small enough to fit in any iPod dock and, once connected to your iPad (or any other iPod product), it will happily stream music from across the room over A2DP, no batteries required. And if you’re using it with an iPhone, it’ll even pause and resume music during a call.
A cool accessory that would go a long way to making an iPad work well with a high-end speaker dock, but unfortunately, it’s not cheap: expect to pay $89.99.
