I only tried one DSD test file so far (DSF I think) and it worked for me, with the 44.1 and 48kHz lights both turning on. Is that what yours does too?
In other news, I got my adapter from Charleston Cable Company for balanced operation. I didn't have a huge amount of time available so unfortunately no pics yet - I chose to listen rather than take pictures and I think that was the right choice.
Going into the options menu, I enabled balance drive. At that point both headphone outs are linked - press either button and both sides turn on or off together. I don't know what would happen if I plug in a "normal" headphone into one side while this option is active, and I'm not going to experiment with it to find out.
I used an Audeze LCD-2.2 with the stock balanced cable, and then also the HiFiMAN HE-400 and HE-500 with a Toxic Cables Hybrid balanced cable (I only have one of these so it had to be swapped back and forth which reminded me how much more I like the mini-XLR connections Audeze uses). So far I'll say that balanced mode is an improvement - a more spacious presentation, and more "drive" for lack of a better word. The "regular" headphone section on the Invicta is already spectacular so it's not a night and day difference, which is just as I suspected. But it does seem noticeable so far. Will it make a difference with all headphones? I don't know. But with these particular models, all planar magnetic and somewhat power hungry, it did matter.
That's about as far as I can go right now based on my limited sampling last night. I notice these findings are similar to when I had the Violectric V181 balanced amp in for review - the differences between balanced mode and single ended mode were not massive but they did make a difference. So that confirms that I'm probably on the right track with the Invicta so far. But we'll see.