Initial thoughts and impressions:
Great tiny size and well made enclosure. I like that it has a rubberized bottom for gripping whatever you place it on. The only audio USB cable I have is a Pangea .5 meter cable. Not sure this is a great choice for portable as it is not all that flexible. I wanted something with some length, so I could use my iPhone to read email, web surf, etc while I listen to music. Trying to put an iPhone in a fixed stack defeats its purpose for me. But this USB cable's rigidness doesn't help and I end up flopping the Herus around. Perhaps just putting an a/b adapter at the end of the CCK cable would be the way to go.
I've only used it with the iPhone so far- computer use will come later. Soundwise it is quite different sounding from the iPhone 5 with iOS7. The iPhone 5 comes across as more laid back, smoother and thinner sounding. The Herus sounds much richer/thicker, more dynamic with bolder, harder hitting bass. Treble is slightly more sparkly as well. It also seems more transparent than the iPhone 5 running iOS7. However that doesn't mean I prefer the Herus in all scenarios.
I really didn't care for the K3003 with the Herus. It was too sparkly and too much bass. I much prefer the K3003 on the iPhone. The F111 was another story. It sounds pretty awesome from the Herus. The bass significantly improves and the treble sounds as good as I've heard from the F111. Another observation is that the Herus as a standalone unit is more accurate and better sounding than the Meier Quickstep too me. Next to the Herus, the QS sounds too bass heavy.
However I'm just not crazy about using the Herus with the iPhone due to the volume control. The Herus has no volume buttons, so the volume is controlled digitally using the iPhone volume buttons. It appears to me that the Herus volume steps are just a bit bigger jumps than the iPhone volume steps, which are already too large when using some IEMS. Maybe it's using the same steps but just seems larger? So finding the perfect volume is somewhat annoying, especially since you typically change volume with different songs due to mastering levels and mood.
So the volume control was looking like a possible deal breaker until I used it with my Bottlehead Crack and HD600. Just awesome. The volume step issue here is negated by turning it all the way up on the iPhone and controlling via the Crack. In conjunction with the Crack, my HD600 is more dynamic with a bit better bass slam; and the big plus is the final bit of treble sparkle I felt was missing when just using the iPhone or iPad directly into the Crack. The Herus>Crack set up looks to be keeper for me.
I'm not sure if I'm going to keep pursuing a portable set up, as I'm just very happy using my IEMS and the iPhone with iOS7. I might try the AK10 sometime down the road, or maybe the Leckerton 760 but for now I'll stick with the iPhone and look into a shorter a/b usb adapter to use with the CCK cable.
By the way, does anyone know where to pick up a lower profile 1/4 to 1/8" adapter? Seems like I've seen pics of them that don't stick out as far.