Thanks guys.
I've read those threads with interest but I wasn't quite sure about the neccesity of having the opposite sides of the drivers pressurising completely different spaces. I now understand (I think) that it's to do with the amount of time/distance between the air movement from the two sides interacting with each other.
I was hoping to build a box that I could then fix into a space when I move into somewhere I can cut holes in! THinking about it, the odds of getting the dimensions to match exactly are pretty slim so I'll probably just hold off until I've got the right environment to begin with.
The idea of a LLT (or even an SLLT) is growing on me though.
Thanks
Conrad