One of the new features in the Canon T3i lets you select full Manual Audio, dial down the in-camera pre-amps, and go all JuicedLink DS214 with headphone monitoring. Damn this is so much easier than all the other random ways to control, monitor, and route incoming audio into DSLR's. If you still liked running a Dual Audio system, you can run a Zoom H1 or H4n on the output between the camera and DS214.

You can see the relative size of JL's DS214 next to the Canon T3i and Rode VideoMic Pro, all mounted on a (gratuitous product shot) of the Juicedlink Accessory bracket. It's such a simple looking setup, but you've got control over the Rode VideoMic with -10db, 0db, and +20db, and then you have a Low / High Gain features in the JuicedLink DS214, along with incoming Right and Left Levels adjustment, and finally piping that into the T3i Manual Audio controls...