Way too complicated if you ask me.
On the previous thread I refered to above I wrote:
I often use a little digital voice recorder to record the intercom during airtests. Saves me from having to write down the numbers during the 5 minute climb (although people have wondered about me talking to myself).
Made an adapter lead with a 3.5 mm plug on one end to connect to the voice recorder and a 6.3 mm plug on the other end to plug into a spare headset socket. In the lead I placed a 67 kOhm resistor and a 47 uF capacitor in series to adjust the output level of the intercom to the required input level for the mic input. Should work on other equipment that would normally use an external electret microphone (as most modern equipment does).
If anybody needs maplin part numbers let me know and I'll try to find a catalogue.
Cheers
Gerard
If you don't have a spare intercom output, you can use a set-up similar to above. Just place a 6.3 mm socket in parallel to the 6.3mm plug. Headset goes into socket, job done. With the series resistor the audio output to the recording device will present very little load to the circuit and won't have a noticable effect on the output level on the headset. This will give you exactly the same functionality as the "aircraft patch cord" mentioned in an earlier post.
Test on the ground before flying, and be prepared to unplug the adaptor if anything goes funny in flight.
Remember, whatever the quality of the mike and pre-amp you use, the sound quality is always going to be better if you take it direct from the intercom output rather than via a speaker/mike/pre-amp set-up. And the adaptor I suggest won't cost more than a few quid to make.
Cheers
Gerard