I don't understand how other people are hearing things so differently from me. As I mentioned in one of my previous posts, I hear the hiss even when the volume is all the way down, no music is playing, and nothing is plugged into any of the outputs.
I've tried both the stock cable and my Moon Audio Silver Dragon cable to see if there is much of a difference - the hiss seems slightly softer with the stock cable, but it's still definitely there.
As others have mentioned, the UERM is not a particularly sensitive headphone, so it stands to reason that the Hugo wasn't made with most IEMs in mind. I do like the fact that there are at least a few slight turns of the volume knob before it gets too loud with most sources, which is more than I can say for most portable amps I've heard.
I've used the "lineout" to my Leckerton amp, which eliminates the hiss, but the sound doesn't seem as crisp or as immediate as the Hugo's amp.
I was also annoyed by hissing sound from my Shure SE846. I bought an impedance adaptor from Ebay: http://www.ebay.com/itm/380932180092?_trksid=p2057872.m2749.l2649&var=650274670628&ssPageName=STRK%3AMEBIDX%3AIT
Now there's absolutely no hissing. Completely black background. The EQ seems unharmed by the adaptor. Maybe the sound is a tiny bit warmer, but it could just be me imagening stuff. One thing worth mentioning is that I had to cut off a bit of the plastic on the adaptor to make it fit the Hugo properly. For 9 $ I recommend everyone to try this sollution. Worked for me.