Back when I had the Metric Halo MIO, some of their analog channels used TRS inputs to save space. In addition, I have TRS ouputs on my ULN-2 that I use a TRS>XLR cable with to my (balanced) amp inputs.
You don't need to hunt too hard for good TRS>XLR cables. I picked mine up at Guitar Center for about $40. You'd just need to make sure you had the proper ends on the cables.