I have been looking for an audio device that will take two inputs and push to the video camera. The Tascam DR-60D is one of those devices that can flip the bill. I was able to check one out while at NAB 2014.
The Tascam DR-60D features High Quality Definition Discrete Architecture (HDDA) in the mic preamp inputs. You can record up to 4 tracks (96kHz WAV) into the device to the SD card or mix it down for input into the camera. That way if one persons audio is too low you can make adjustments after.
The DR-60D contains an adapter shoe to place in-between camera and tripod. 4-AA batteries power the unit and can record for up to 4 1/2 hours. The unit weighs under 1 lb for portable rigs. A remote control can be added (sold separately) to start and stop recordings.
Get the Tascam DR-60D through B&H