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Raja explained how the three Essence One versions differ to reflect the price structure of $599, $699 and $899 for the Standard, Plus and Muses respectively. "The difference is in the op-amps. The only other minor change is that we included a gain jumper on the Muses Edition. This alters the output voltage for someone who wants to use IEMs which won't require as much gain as over-the-ear designs. Setting that jumper to the alternate position lowers the gain and thus achieves more range over the volume control. The Plus Edition includes 4 x TI-OPA2132PA and 2 x NS-LM4562NA that can be interchanged with the standard NE-5534. The Muses Edition simply has the version 01 Muses by default as the very best we've found. It thus ships with no other op-amps to swap. If a user wanted swap options out of the box, the Plus Edition would be the one. For obvious reasons the Plus includes a screw driver and two IC clamps plus step-by-step instructions and the op-amp guide of our listening impressions. The Muses op-amps are of limited supply and I believe one of the very few places in the Western hemisphere to even sell them is Digi-Key. Last time I checked they were $50/each."

Très chipper! Were the standard edition a Chinese 300B valve amp, it'd come with Shuguang's cheapest glass. The Muses Edition would arrive with Czech Emission Labs or EAT bottles. That this converter runs six of these costly chips reflects on the buying power of Asus and on the retail offset with the base version. Had I expected out-of-box rolling with the Muses, I'd misunderstood. But since it most likely goes downhill from here, that actually made perfect sense. Even so the Muses remain socketed for those disagreeing. They can still be swapped.

Before we perform our mandatory laying-on-of-ears routine, some background on the bigger game. For this Rajinder Gill introduced me to Dave Chen and Ives Chiu, product managers who oversee Asus' R&D department. I sent them 11 questions. They and their replies follow.

1/ As a computer company supporting standard users and gamers, what were your design goals to appeal to the hifi/audiophile market in particular? How did your design brief for the Essence One diverge or overlap with that for the ST sound card for example? Was it about different circuitry, more upscale expensive parts, better measurements? How was better sound qualified and ascertained?
Being a computer company, we were very aware of how PC/digital devices would become one of the major sources for music listening and started to plan our strategy years ago. We figured that having a 'computer company' image, it would be time for people to change their perception of the brand. Back in 2007 when we first launched the Xonar line, rather than move into the hifi/audiophile market right away we started to produce consumer sound cards to first establish the Xonar brand. In 2009 we launched the Essence STX/ST to move deeper into 'audiophile' territory. For us these are 'middle-of-the-road' products which also suit other scenarios like gaming if you don’t require multi-channel surround output.

The Essence STX/ST happened to really strike the interest of audio enthusiasts in various online communities. Now we figured the time had come for a serious audiophile product. This started work on a prototype which eventually became the Essence One. With an external device we had more flexibility with power and PCB space. Compared to the Essence ST the Essence One adopts a linear power supply and dual-mono DAC structure. These things are not easily implemented on internal sound cards due to space constraints. For the end user the USB interface also makes it easier to run than an internal sound card. For us the Essence One is all about better sound. To qualify design and parts choices we compared the Essence One against competitors and also against the Essence STX/ST to ensure we were on target.

2/ Who do you consider your competition for this model and what actual competitors did you evaluate to gain a base line for the current status quo in this sector?
We looked at products from Cambridge Audio, Burson, Benchmark, TEAC and NuForce. We believe that above a certain price things become very subjective. So we listened to a whole slew of products. We didn’t just define a group of target specifications. We voiced many parts and compared our design to competing ancillaries to see if our design brought out their best.

3/ What headphones did you try with the Essence One? What are the actual power ratings into 32Ω, 50Ω, 100Ω, 300Ω and 600Ω?
We have Sennheiser HD650/600/800, Beyerdynamic DT880 in both 250Ω and 600Ω, AKG K240DF and Q701. We also have some low-impedance units like the Sennheiser HD280 and some Audio-Technicas. For IEM we use Shure 535/310 and Sennheiser IE8 (borrowed and having us very reluctant to return). With 600Ω headphones the output is around 75mW. 32Ω corresponds to 650mW, 50Ω to 610mW and 100Ω to 395mW.

4/ What main systems did you try with the Essence One in DAC/preamp mode?  What is the reference system at Asus HQ which tested the Essence One during prototyping?
We used a variety of desktops/laptops in USB mode and did not find the sound much altered between different PCs assuming bit-perfect output. We keep our OS clean and install minimum applications. For S/PDIF we used BD players from Samsung and Sony together with our own media players.

For speakers we have a few different passives and actives. The most used are Adam A5 active monitors. Those are neutral yet highly revealing and thus excellent for assessing critical parts choices.

5/ Why the dual volume controls? Isn't it highly unlikely that anyone would ever listen to headphones and speakers at the same time? From a cost perspective, wouldn't a single volume control for twice the money offer superior performance over two for half the price each?
If we apply a single control for both outputs, users may need to adjust the output level while changing from headphones to speakers and vice versa. We figured that it would be more convenient if we provided separate controls.