ASUS's style is debatable, it is certainly not the prettiest unit on the market and the many blue LEDs just look a bit misplaced, definitely not what you would expect to see on a $600-ish performance headphone amplifier.
The logo on-top is the golden dragon we have seen on a lot of ASUS sound products. Oddly enough the top part is curved making it impossible to stack something on top of the unit. The surface coating system used makes it a bit of a finger print magnet, fortunately the coating is well executed and will probably last a very long time even with regular cleaning.
The business end of the ASUS Xonar Essence One is relatively well laid out. The placement of the headphone jack is good, but the small headphone volume knob is quite hard to reach when you have inserted a headphone with an over-sized 1/4" jack. It would be better if the central digital volume controller and the headphone volume controller were swapped, since it is unlikely that there is anything plugged into the headphone out while the digital out is in use.
Again the layout is semi-cramped, but looks alright. The knobs have a very average feel to them and it is hard to adjust them properly.
This ASUS unit has a lot of good connectivity options at the back. You get balanced outs, digital in via optical and coax, and a set of RCA outs as well. This is really good considering the price of the unit. Kudos for including balanced outs, I am sure that a lot of people with active speakers will find good use for them.
The back side of the Essence One is well laid out. The unit is passively cooled therefore the back plate is perforated.
ASUS's design oddities do not stop with the curved top plate, also the bottom is profiled which again makes the unit a bit harder to stack. The small natural rubber feet are OK, but it would have been nice to see something beefier that provides better vibration reduction. Given that rubber feet do not cost a lot it seems a bit odd to skip this upgrade from a manufacturing point of view.
With the top off you can see where ASUS's design focus was with this unit. The components used are of a very high quality throughout the unit, and the many swappable op-amps are a delight for tweaking audiophiles.
The Burr-Brown PC1795K DAC in the unit is one of the best sounding on the market today, and it accepts 192 kHz / 24-bit which makes it capable of converting the highest quality source material available online.
ASUS uses an Alpha pot to control the volume for the headphone out section. The way it is integrated means that there is a channel imbalance occurring every second step, effectively halving the resolution of the volume pot. The volume imbalance is around 1-2 dB which makes it noticeable through the headphones. Since the imbalance is present throughout the volume control's reach it is an extremely annoying bug, especially when you are using high sensitivity headphones.
A relatively big toroidal transformer powers the unit.
Clicking the image above gives you an ultra-high resolution stitched image for those that want to see the details. The NN5532s are swapped for LM4562NAs on the picture above, otherwise it depicts a stock Essence One.