The LT DOES NOT have an Aux In. I use my iPad to play backing tracks when I play. I use the USB cable into the USB port and then an Apple adaptor to change from USB to the USB C connector on the iPad. This works great for me. The only thing with doing it this way, is that you cannot control the volume of the iPad with the ipad’s Volume controls. The volume of the iPad needs to be adjusted in the Helix Global settings which is only a couple of clicks from the main screen so not a big deal.
There is another way of doing it with the send and return I think but I don’t know how to do that so someone else will have to help with that.