Xpantastic!

I recently got an Xpander, and although it's incredibly deep, six voices isn't much to play with.

Is there a way to pair up two Xpanders (short of hunting down a Matrix-12)? Or even more than two?

There are some references in the manual to using the MIDI ECHO function (see page 50). It seems like this would work, but I wanted to see if anyone has experience using multiple Xpanders in this way.