I've been reading some of the latest posts about RED and its audio capabilities. As a sound recordist and studio owner... I would recommend that new owners of the RED ONE take the necessary time to read the manual and
order 4 Mini XLR - XLR adapters and 4 mini XLR cables from RED.com. Cost about $180.
Next pull out an available microphone (Dynamic or Phantom Powered Condenser) and connect it to one of the 4 audio inputs on the RED via the cables you purchased. Any microphone that has a sensitivity of -20 to -60 should work well with the RED. Using the menu turn on Phantom Power to the input you are connected to if you have a phantom powered condenser mic.
Next, speak in a normal voice and check the levels on your VF or external monitor. Don't go into the red... pun intended. Record about 30 seconds.
Playback the audio. Does it sound distorted? Then you need to adjust the Record levels a bit. if your audio is still distorted, then you will most likely want to run your mics through an outboard mixer like the Sound Devices 442. That way you can connect up to 4 mic/line sources and take the Direct Outs from the mixer into the RED. You will have much better mic preamps than the RED by a longshot. You will also have input and output limiters at your disposal. Remember to set the Audio Input(s) to Line In if you are using an outboard mixer.
I would NOT recommend trying to record with a camera mounted mic due to the fan noise... in fact you need to be about 6-8 ft. away to not record fan noise. However, you could try to blimp the camera, but watch out that you don't overheat the camera.
A bunch of forum folks have decided to go the 2 system audio route which will work just fine... as long as you have a Timecode capable audio recorder to use as the Master and Jam Sync the RED via a LEMO Timecode In/ Out cable. This is easily done with the System 7 recorders from Sound Devices. Don't forget to purchase a smart slate like the Denecke TS-C or their other smart slates and a LEMO to LEMO timcode cable... RED.com sells a 10' cable.
2 system audio is great as long as you have a sound recordist, smart slate and someone to clap for you and undertand the finer points of Digital Audio and Timecode. It doesn't have to slow down production that much. The more organized your crew is, the better. Using a timecode slate can speed things up in post in FCP or AVID.
You can still record usable audio direct to the RED... Just take the time to read the manual and experiment before you are actually into production. RED.com tech support is also available to help you out with settings and questions.
If all else fails... get in touch with a sound recordist who can possibly help you out before or during production.
Best of luck to all... Awesome audio is right at your fingertips!