You did mention on your page that you don't actually need the ac/dc connector for power, but only for detection correct? If that's the case, have you already considered simply getting a small plug of the same size and use that in your wooden block instead? That would avoid putting the adapter in the box and you could use it elsewhere.

Thanks for the comments on measuring. I had assumed that much already, but it's good for people just jumping into the thread that don't have to scratch their heads. Really good idea with the block though - simple, stable and it lets you do multiple connectors with one attachment point.

Bruno