OSX aggregate device only allows 32khz sample rate?

Mark Durham's icon

It's the first time I've used this feature of OSX, so hoped someone may have encountered this before. I'm using 2 Avid Mbox2 mini's as an aggregate device in OSX to get four outputs for a surround piece. Max will only let me select a 32khz sample rate for output? Other programs are fine with 48khz.

Any ideas?

Max 6.1.3 32bit
OSX 10.7.5
Macbook pro 13" mid 2012
Processor 2.5 GHz Intel Core i5