Why when the Zoom H6 is also an audio interface?
Because back up.
The Zoom H6 does not record and act as an A/I at the same time (I believe the Zoom LiveTracs can do that now). So I take the line out from the H6 and use the two inputs in the Zoom U-44. Now I can record and/or stream on my computer using the DAW or OBS.
I’m all about back up. The other thing I could have done is use the H6 as the A/I and use the line out into another recorder like the Zoom H1 or H4 but that would sacrifice the sound quality I get by recording the individual tracks on the H6. I like to play guitar and do some vocals every once in a while so using this set up allows me to not have to move around so much and just pressing record on the H6.
If you really want to get crazy, you can use the headphone out from the H6 and send that to another recorder like the H1 or H4. I’ve had cards fail before and computers crash so on an important interview/podcast/jam, it would be great to have a triplicate.
If I were doing a live stream with a live band, I would use a similar set up but maybe use a Zoom R16/R24 (or any basic mixer if recording individual tracks is not important) for additional inputs or use one of the Zoom LiveTracs which I am considering in the very near future.
I’ve been podcasting enough now to realize that a backup is absolutely paramount.