I posted this question in the sound forum but didn't get any reply, maybe I'll have more luck here.

I need to use both channels of 16bits audio on the XL2 for a shoot but the second channel is a fixed ambiant sound and doesn't need to be monitored. The first channel on the other hand will be dialogues and the soundman needs to ear this channel both in the left and right speakers of his reference monitor headphones while shooting.

As it is, when you plug the headphones in the camera headphone jack, you hear channel 1 on the left side and channel 2 on the right side. You can select the "REC CH. SELECT CH1-CH2" option but then you won't be able to record two distinct tracks of sound.

I went to Radioshack thinking they might have some kind of gadget to plug a cable in the 1/8 stereo headphone jack and split the XL2's left channel over both left and right sides without degrading the sound, but they don't.

The salesman told me though that Canon made such an adapter for this specific use, but I never heard of it nor seen it anywhere. Don't know if he was just trying to get rid of me or if in fact there is an adapter made by Canon for this very purpose.

Anybody knows about that adapter? Or maybe an other similar adapter that will allow me to do this? A custom made work-around maybe?

Any help will be greatly appreciated.

An addapter should be pretty simple to assemble. By a female headphone connecter (I believe this is a standard 2.5mm stereo connector) and connect the center conductor of a piece of shielded cable (doesn't have to be - twisted pair would work as well) to both the tip and ring lugs. Connect the shield to the sleeve lug. Now solder the other end of the shield to the sleeve lug of a male headphone connector and the center conductor to whichever one of the two channels (ring or tip) you want to listen to or get fancy and solder the center to the common on a SPDT switch and connect the other two switch lugs to, respectively, ring and tip lugs on the male plug. You can now use the switch to select whichever of the two you want to listen to.

Interesting. Won't I be losing audio quality if I split one channel over two wires? I assumed I needed some kind of amplification to preserve the signal (or to double it, not split it). It's important the soundman hears exactly what will be recorded on the tape.

I like the switch idea.

Since you will be driving two transducers from one amplifier the sound in each will be at least 3dB lower in amplitude than if you connect one transducer to each amp and you are also potentially mismatching impedances which will result in even more loss. A tweak of the volume control should make up for this. You should not lose sound quality but you can be the judge of that by comparing the normal use of the headphones with this kluge.

More elegant solutions would use a pair of buffering amps driven from a common input stage which would sample one channel or the other from the headphone jack.

If I can compensate the loss of signal by cranking up the hearphones' level without introducing any kind of distortion, this splitting adapter might be a viable solution. I'll give it a try, thanks for the help.