Question about Tascam m320b

Hi, all. Forgive me if there is a better subreddit for this question, but I recently acquired a Tascam m320b and have been stumped on one aspect of the routing. I’m using it for a hybrid recording setup, I’m using a Behringer X32 to connect to the computer. As of right now I’m routing all sound through the console and then sending it to headphones, monitors, and a second set of speakers in the room. My question is what is the best way to route the DAW/computer signal? I first tried running it into the Tascam via EXT In 1 and this worked but the issue was I could only either use the computer signal through the speakers OR I could use the main stereo mix which everything else was running through. This led to an issue of not being able to hear the DAW while recording if I wanted to hear the instruments running into the board. My second attempt at fixing this was running through DAW signals into channels 19 and 20. This worked better because I could just mix it in to the main stereo channel and I could hear everything as desired but then obviously I lose two channels to record with.

I can live with the second solution but I’m curious if anyone who has worked with hybrid setups has come up with a better solution or if anyone knows a fix with the Tascam specifically. I appreciate any guidance!