I thought the other thread was dead due to this amp is not the latest new thing given it's been around since 2012.
Anyway, I'd like to share my experience with this amp, and it has been a good ride since I've gotten it. Interestingly, this amp is pretty under-valued used, and if I compare to something like GSXMK2 which goes for $3k, I find this amp to be the better value, and performs better. Only thing is that low gain is still pretty high for sensitive headphones. This has lots of power, and shouldn't be lacking power to drive pretty much all headphones to proper sound output.
Interestingly, balanced output sounds different from single ended (this is one of those amps that I know for sure does). Puts out punchier and upper-mids forward sound that if you think your headphone needs slam and punchiness, it would most likely delivered with balanced output (I wouldn't recommend doing this for sensitive headphones as it have too much gain for easy to drive headphones in balanced). I've been using balanced with the HD58X, and sounds like a different headphone from single ended. It really does sweetens the headphone to much better value than it's tag price.