Pros: affordable PNP solution to audio bliss
Cons: very bright front panel LED's
So a friend of mine finally received it last week and allowed me to play around with it while he's on vacation so I could get to hear whether all the Muses hype was true(someone on another forum claimed that it killed AD797 to his ears).
Just as a short reminder, the Essence ONE runs a dual-mono design from start to end, based on two PCM1795 DAC chips(the same one you can find in many megabucks DAC units) and 11 dual opamps, as described here:
Asus clearly went as "discrete" as you can get with opamps through a fully dual-mono design, and also using separate dual opamps for all +/- polarities allowing for the least crosstalk and the cleanest signal you could posssibly hope for.
All inputs are also reclocked through a 900 MFLOPS 40bit float DSP from ADI: http://www.analog.com/en/processors-dsp/sharc/adsp-21261/products/product.html
The S/PDIF receiver supports up to 24/192(and never glitches up on sample rate changes): http://www.asahi-kasei.co.jp/akm/en/product/ak4113/ak4113.html
The USB controller supports up to 32/192 and abides by the "USB Class 2" specs so it will only require drivers on Windows(that also come with native bit-perfect ASIO 2.2 capabilities) and will work as PNP on MacOS and Linux: http://www.cmedia.com.tw/ProductsDetail.aspx?PSerno=43
I should also state that this USB controller is self-powered from the internal toroidal transformer and still works perfectly fine after you break the 5V pin of the USB cable so don't expect miracles from USB PSU's for that matter, as none will ever occur(breaking the pin would also supposedly improve SQ from what SOTM are claiming).
The headamp also runs in dual-mono with two of those chips and each of them can output up to 250mA(the average opamp is capped at 50mA max, often a lot less): http://www.ti.com/product/lme49600
All this to say that Asus have been making highly overclockable computer parts for quite some time so you can always count on their R&D to provide their expertise in PCB design, as stereo audio is probably child's play compared to a TOTL Ghz-range computer board meant to be cooled down by liquid nitrogen
Much has been written about the regular ONE and I'm sure you can easily find dozens of reviews of it via google as the ONE really took the standalone DAC market by storm.
Differences between the regular ONE and the Muses edtion go as follow:
1) opamps in positions 1 and 2 have been replaced by the market leading Muses01 opamp from NJR: http://semicon.njr.co.jp/eng/MUSES/MUSES01.html
2) the PCB has been revised in order to provide a jumper to set the headamp gain in either LOW or HIGH position, as the regular ONE came with its headamp set to HIGH and this was a bit of a potential issue with low impedance/high sensitivity headphones for people who don't listen at loud volume.
3) the regular and Muses edition are using different pots(B10K>A10K) on the headamp: http://www.taiwanalpha.com.tw/english/p_e_70-1.htm
All I can say compared to my "Stello Eximus DP1" is that deep bass is back with a vengeance! But I'll give you that the DP1 is pretty bass-shy to begin with(hence the "filter" megabass button on its front panel right under the phone output, reason why many people like to pair it with a beefy tube headamp). Also the SS shape is rather different, the DP1's strong asset is its "live sounding" SS when this Muses01 ONE really excels at mids, and the SS is really completely differently shaped.....I guess opamps rollers are well aware of how opamps can modify the SS perception and when the DP1 colors the SS by breaking it into many 3D layers, the Muses ONE makes it sound more like a "sphere" so to speak...it feels more "natural" but also less expansive. But the DP1 costs three times more than the Muses ONE so put my opinion back into context as the SS is still very wide and clear, presenting a sort of "holographic" instruments separation that surely will take you by surprise. Stereo jitter performance(at which the DP1 is considered a benchmark) appears most excellent as well.
Textured vocals(recorded with Neumann U87's for instance) really sound as true to life as it gets, I'm impressed to say the least.
Of course, my friend's got the headamp gain switch:
With the gain set to high, my favorite 150Ω yamie ortho still sits at 9 O'clock just like with the regular ONE. OTOH, with the gain set to low, it's more like noon, quite a bunch of much required headroom indeed! Stereo tracking appears perfect to my ears(I guess that might also be part of the reason why they went A10K instead of B10K on the headamp).
Anyway, it seems rather clear that when the regular ONE felt a bit like unfinished business due to its entry level swappable opamps and high headamp gain, the Muses edition addresses both issues brilliantly and the 6moons review conclusion couldn't be more spot-on IMO as I can only agree that if you seek serious bang/bucks, the Muses ONE should seriously be considered.
You can surely get better sounding gear, but it'll cost ya. I would presume that entering the serious DAC market segment was quite a bet for Asus but the ONE has finally reached maturity to my ears...getting this kind of performance out of the box under a grand is darn impressive
A few hours have passed and after more critical listening, the center of the SS really feels as if the singers were standing in the room...and the texture of the mids is really worth all the Muses hype to my ears. Hi-res sounding and yet not too sterile/clinical sounding, yay!
OTOH, when the DP1 tends to make everything enjoyable the Muses ONE is rather unforgiving on subpar recordings....it will not hide defects in order to provide permanent euphonic enjoyment so you'll really have to polish your source files. To my ears, the Muses ONE sits nicely between the colored hifi DAC that makes everything dreamy sounding and the harsh monitoring DAC designed to make you hear the defects more than anything else....so you get a highly enjoyable reference DAC that neither hides the truth or tries to make defects more audible than they really should be(which become an asset when you realize that the average record has gone through hundreds of 5532/5534 opamps).
I believe this reloaded ONE puts back into perspective the ridiculous amounts of money ppl can/have to spend on boutique DAC's, headamps, shaman blessed USB cables, jitter-prone S/PDIF transports, battery based PSU's that all together can easily reach the $5K bar when the Muses ONE provides such high bang/bucks for quite a bit under a grand. I finally got to hear what my friend's enthusiasm was all about, and movies/70's female vocals are truly something on the latest offering from Asus indeed. IMHO you have to be seriously demanding/OCD'ed to turn down on what the Muses ONE has to offer, gg Asus
Also, the ONE isn't amnesic.......you can plug it off, plug it back in days later and it will remember what the last active input was and whether upsampling was engaged. This might seem like a detail but that's the kind of feature that quickly gets on your nerves when it's not the case(talking from personal experience here ).
The only thing I don't really like is the front panel bright LED's as I usually watch movies in a pitch black room but that's nothing some black masking tape can't fix.
PS: if you're from team "unmodified = not worth listening to" then you can still roll the opamps in this pimped edition of the ONE, but quite frankly I would leave the Muses opamps alone. Opamps might look like $0.1 lego bricks but they really aren't and these integrated components were a literal technological breakthrough when they were invented. All this to say that playing God by rolling any opamp "that fits" can end up in audible glitches/wooshing(due to stabilty issues and oscillation) or worse..
You really have to stick to "unity gain stable" opamps and they also have to come in DIP8 packages and have to be two channels "dual opamps" and not one channel "single opamps". You can still find single opamps soldered onto dual adapters, but if one of them is faulty or soldered in the wrong direction you will brick your ONE(and good luck with RMA)...so I would personally advise to only buy from well established sellers that claim every module to have been tested before shipping and I would triple-check that every opamp is properly soldered and every module has been inserted in the right direction into the ONE.
Asus are kind enough to provide an opamp rolling guide: https://www.google.com/search?q=Xonar_Essence_One_Opamp_Swap_Guide.zip
Personally, I would simply swap the LME49720NA's with the dual OPA2132P opamp or single OPA627's on dual adapters, but the latter is the most counterfeit opamp so I would buy OPA627AU's from an authorized dealer, have them soldered on dual adapters or buy them PNP from someone highly trustable. OPA2132P is a safe and cheap trouble-free bet and is famous for its warm and yet detailed sound, so much that I can only agree with this statement: http://tangentsoft.net/audio/opamps.html
I've personally soldered, rolled and heard dozens of opamps and when AD797 or LT1028 aren't "unity gain stable" and often tend to get cranky(leading to audible artifacts) hence requiring a tailor-made surrounding circuit, OPA2132P is very sociable and always a reliable ally IME. There's a very good reason why many expensive DAC's embed it and Asus recommended it in their opamp rolling guide
In one sentence, I would simply say that the Muses ONE allows you to get one foot in the high-end audiophile door without writing a 4 figures check.
This is my first formal head-fi review using this form and I hope to have shed some lights on this great little unit and managed to share the enjoyment