One question we’ve been asked a lot since the release of the newest iPad 3 is whether or not it is compatible with the Alesis IO Dock. Unfortunately, the official answer from Alesis is that they are not compatible.
The problem seems to be that the 30 pin connector of the new iPad 3 is slightly off (different) from the old one, and Alesis does not recommend forcing a connection with the iPad 2 insert.
There is a lot of good information here, including a recap of some of the official answers from Alesis:
We’ve been big fans of the IO Dock here, and we’re looking forward to the release of an iPad 3 compatible version as much as anyone. Please let us know if you’d like us to update you with any news on this,