Dynon altitude encoding to TX 327 Txpnder

I was planning on using the Dynon D10A altitude output as the altitude encoding for the Garmin GTX 327 Txpnder. However I note in the Dynon installation instructions it says the altitude output is not corrected for pressure. I haven't been able to find anywhere in the Txpnder installation guide that this is satisfactory or that there is some compensation for that in the transponder. I am thinking I might use a Garmin 430 GPS output to provide the altitude for the transponder.

I want the transponder to transmit the correct altitude. Any useful information on how to acheive this?

I thought it wasn't supposed to be corrected for pressure.. atc does the correction...

ALL altitude encoders transmit altitude based on an altimeter setting of 29.92. The altitude is then corrected at the receiving station.
Mel...DAR