Bryan & John - I have searched the Kenwood documentation and can't find a spec for the Data Input line on the 13 DIN connector. That said I have found a mod that changes where the Data Input ties into the transmit audio chain. This is a known issue on the TS-440s. I have a Signalink USB that I use with the TS-440s and I have to run the TX gain on the Signalink and the MIC gain on the TS-440S at maximum to get about 25 watts out on FT8 running at 1,000 HZ. So , it is not a short coming of the DRAWS card.
The Issue: The issue is that the Data Input on pin 11 of the 13 PIN, Accessory 2 connection does not go into the mic preamp of the TS440s. The mic gain does still control the overall input level but without the preamp is appears the drive level needs to be 5 volts peak to peak or more.
The Mod / Fix: Here is the link to a mod: https://www.qsl.net/9a3og/kenwoodts440.html
These is a AFSK Input RCA pin plug jack on the back of the TS-440S. This input does pass through the mic preamp. This mode moves the connection from the RCA jack to Pin 11 of the 13 pin DIN. I have not done this mod yet but have reason to believe this will resolve the drive level issue.
Mike - KB0FX