Also make sure of the version of the MixPre you're using. An early version had an impedence balanced output with the entire signal on pin 2 only. A normal balanced pad won't attenuate the signal by the amount indicated on the pad. You also won't get the normal -6db drop if you only use pin 2 with an unbalanced adapter.
The newer versions of the MixPre with a regular balanced output also have a 4-pin power connecter versus the original barrel-type power connector. That's the easiest way to spot the difference.

How much pad do I need? 10dB, 20dB, 30dB, or ?

Jay, are you saying the newer MixPre's pins allow the pad to function correctly?

The Canon has a built-in mic attentuator that will take care of part of it. I don't have all the numbers in front of me but I think its around -20db. Mic input sensitivities are gernally in the ballpark of -50db so the 20 or 30 db pad would be the one. Several manufacturers make switchable pads that you can vary as needed. You might also consider something like the Beachtek DXA-4, -6, or -8 at the camera end instead of the MA300 as they are adjustable between line and mic sensitivity. Take a look at www.beachtek.com for details.

Steve, thanks for answering the pad question.

The GL2 attentuator is -20dB.

I was considering using both channels in the GL2 to have another track for insurance. Using a BeachTek allows only one channel via the mini-plug to the GL2, right? and I still need the mixer. (for the boomed AT4053a)

Check their specs on the web site - The Beachtek has two XLR connectors and I'm pretty sure you have a choice of sending one of them to both channels in the camera or sending one to the left channel and the other to the right.

The beachteks have a 2 mic inputs and have one stereo mini-plug for the output, so how can I control the 2nd channel for the "insurance track" on the GL2 or any XLRless camera?

I don't have one but I understand the Beachteks have a mono/stereo switch that lets the left channel XLR feed both the left and right inputs in the camera. If you keep the MixPre at the boom operator end, use its internal oscillator to send a 0db tone down the line to the camera to the Beach. Switch the camera to manual level control, switch on its internal attentuator, and set the camera's gain control for the left channel to about the 2/3 point. Put the Beach in "dual-mono" mode so the left XLR feeds both channels in the camera. Without changing the camera's level setting, adjust the control on the Beach so the reference tone shows at minus 12db on the camera's meter. Now adjust the camera's manual level control for the right channel so the tone reads minus 20db on the right channel meter. Ridin gain to control the actual audio level during a take is controlled by the mixer/boom operator using the MixPre where the 0dB meter reference will represent recording levels of -12db & -20db at the camera.

You could also use 2 parallel XLR cables between the MixPre and the Beach/Camera end, one for each channel and set the Beach to stereo mode. The mic is panned to the centre at the MixPre so the same signal goes down both channels to the camera. Use the same technique for setting levels.

Your audio wisdom is appreciated.

I was reading Double Spotted Eagle's response in the "another audio question" thread--he stated you don't need a mixer for a one mic shoot. Could I still get good sound using just a beachtek with my boomed AT4053a?

I overlooked headphone monitoring.

I've read that the GL2's headphone monitoring is weak. If a mixer is not needed, would a good choice be the Sound Devices MM-1 instead of the beachteks?

The SD MM-1 seems to have more control for a one mic set up.

Not really - while the MM1 is an excellent unit and highly recommended it would replace the MixPre, not the Beachtek. While Beach has a couple of preamp equipped units, the version I've been kind of assuming you'd be using would be the basic DX4 which is a passive device that a: pads the incoming line level back down to a mic level, and b:interfaces the balanced feed line from the boom end, whether it's coming from a preamp or a mixer, to an unbalanced stereo miniplug that the camera itself wants plugged into it. It also blocks the 5v bias voltage the camera puts on the input that is needed with a consumer grade electret condener microphone but can degrade the performance of pro gear.

Both the MixPre and the MM1 provide headphone monitoring to the boom operator.

So a boomed mic (AT4053a) connecting to the input of the SD MM-1, the SD MM-1's output connects to a BeachTek DXA-4P, it's mini plug to the GL2.
This configuration seems like it will do the job well.

Steve, using the GL2's mini-plug allows you only to use the camera's left channel only so how can I use the method you suggested in your reply #22 (Using both channels on the GL2)?
Or am I just confused?

I may be wrong but I was under the impression that the GL2 mic input was stereo to accomodate stereo (2-channel) mics and so would acccept a stereo signal on a TRS miniplug connector at the mic connector. You might be thinking it's mono because the simple XLR to miniplug cable adapters are wired for mono to a TS miniplug but the Beach output is TRS and connects to both channels.

Thank you much for clearing that up about the beachtek.

Is there a way I can do the "extra track method" (insurance) with the SD MM-1 connected to the beachtek DXA-4 instead of the MixPre? Thanks!

Sure - the camera has two level controls, one for each channel. Your mic feeds the MM1. The output of the MM1 is connected to the left xlr connector on the Beach and the right channel is turned all the way down to prevent noise from creeping in. The Beach stereo/mono switch is set to mono. This puts the input signal on the output's left and right channels equally so whatever is going to the Beachtek's xlr connector will be recorded on both channels in the camera. The camera is set to manual recording level control and you adjust the camera's level controls so they're about -12db on the left channel and -18db on the right. The only real drawbacks of using the MM1 instead of the MixPre is the lack of a built-in standard reference tone to help set the gain staging along the chain and the lack of a level meter. Personally I'd go with the MixPre in order to have those two features.

Those two features are important, I'll take your audio sage advice and go with the MixPre instead of the MM-1.

Steve, you've broke-down my questions, gave great tips and saved me a lot of headaches. I'm going to put your name in my movie credits under Audio Consultant, unless you prefer a different title.

Since I'm using a boomed AT4053a for both indoor and outdoor settings, what should I use for the AT mic outdoors to get good sound? Windshield/blimp, mic techniques, what else?

Once again in detail: the outdoor scenes will be shot in a small backyard patio that has a low wooden roof, a concrete floor and lots of plants & shrubs in and surrounding it. The four actors will be sitting very close to each other in a circle.