Not much wiggle and hear himself

positive:
* Processing with one exception (see below) very well. Very stable housing and Poti. Little distracting power LED.

Negatives:
* The docking port for the DAC is not as good. The DAC has pocketed much game so I'm afraid that the connection could break, if I come across a little stronger even accidentally to the DAC. Even when slip in and out of the DAC has much play at an angle, so that you also get here is worried abort the actual connection.

Sound:
I have no other KHV as a comparison, therefore describe only the difference to E07K. When I run the E07K with the E09, I think, to hear an improvement of the sound. However, this is quite subtle. Technically, the E09 but has the more powerful amplifier. In other headphones like the improvement be clearer.

Conclusion:
Almost perfect workmanship. If you want to let the DAC FiiO anyway in the E09, there is nothing to complain. A sound enhancement for E07K was subtly noticeable. I recommend to test here with their own headphones if you hear an improvement.
You can operate as a standalone KHV the E09 course. He is a very good and favorable improvement over most headphone outputs.