Audio-Opus OPUS #11

General Information

Ultra Slim Portable Audio Amplifier and
USB DAC (Digital to Analog Converter)
for your smart phone,

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Pros: Sound quality, value for money, size, internal battery, great Android compability
Cons: Low on inputs and outputs
This is a review of the bit Opus #11 dac/amp.
The bit Opus #11 was purchased by me directly from the bit.
It’s available for purchase around the same price from HiFi Headphones UK:
For more information about the bit Opus #11 you can also visit the bit website:
I’m not in any way affiliated with the bit or HiFi Headphones.
Short introduction to the bit:
The bit is a Korea based company founded in 2004.
This is what they say about themselves on their website:
  1. Specialized in designing and development of ICT devices, including MP3, PMP, NAVI, Digital TV etc.
  2. The staff of the Bit consists of highly specilized high-tech engineers, who possess a valuable knowledge and experience in developing set top box, etc. within Samsung Electronics
  3. R&D family members formed a tight teamwork for the last 15 years, that conduced to the successful mass production of MP3 players for the first time in the world.
  4. Stable and reliable supplier of featured products for Samsung Electronics, Best Buy and SanDisc in United States.
  5. PND consumer products export to Japan for 3 years, proving the highest quality of manufactured products.
  6. Possession of the wide variety of technological solutions, including the ARM, WinCE, Linux, Android OS etc.
About me:
I’m a 44 year old music and sound lover that changed my focus from speakers to headphones and IEM’s about five years ago. At that time I realized that it wasn’t realistic for me to have all the different setups that I wanted and still house a family of four children and a wife so my interest turned first to full sized headphones and later also IEM’s.
My preferences are towards full sized open headphones and I believe that also says something about what kind of sound signature I prefer (large soundstage in all directions, balanced and organic sound).
My music preferences are pretty much all over the place (only excluding classical music, jazz and really heavy metal). My all-time favorite band is Depeche Mode although I also listen to a lot of grunge/indie, singer/songwriter/acoustical stuff as well as the typical top 40 music.
I tend to value function over form within reasonable limits.
I do not use EQ, ever.
I’m a sucker for value for money on most things in life Head-Fi related stuff is no exception.
Built, accessories and functionality:
The bit Opus #11 is an amplifier and DAC combo.  
The bit Opus #11 is available in only version/color as far as I know.
The maximum output power is rated to 125mW@ 32Ohm and output impedance is rated at 1.2 Ohm.
The Opus #11 has a sturdy metal housing that feels durable. There are no physical controls on the unit whatsoever so volume need to be set on your source
The Opus #11 offers one USB micro digital audio input and a separate 5v input charging port. Since it can also charge from the micro USB port combined with the lack of an included 5v cable I’ve not tried to use the 5v input for charging. There’s also one 3.5mm single ended headphones output. Theres’s also a couple of led lights where one indicates whether the unit is charging or not and the other indicates the battery level as well as confirming that you’ve go at working USB connection. 
The design is very clean and simple so it’s really not much more to say about it.
The Opus #11 works extremely well with Android devices when connected with an OTG cable and using USB Audio Player Pro (UAPP) as music player. A nice feature is that it disconnect automatically from the Android device when the headphones are unplugged from the headphone jack as this turns the Opus  #11 off. This means that you won’t have to disconnect it from the source every time you stop listening to save power. The internal battery on the Opus #11 does also make the battery drain on the hosting device very low. Although Android and sound does not have a great reputation the Opus #11 have worked with every Android device I’ve tried it with not only with the help of UAPP but it also actually work great with streaming services like Spotify which is certainly not always the case with these kind of devices.
The Opus #11 uses an Xmos USB receiver that is supposed to work with Apple devices using the Camera Connection Kit (CCK) but I haven’t been able to test this myself.
The battery life is fairly good and is said to be 8 hours, without having brought out my stop clock I’d say that these numbers are fairly accurate from my experience. The power required by the headphones or IEM’s your using will of course also affect the battery life. Charging time is about 4 hours and although it’s quite long it have not really bothered me since I typically charge it when I sleep.
The Opus #11 support all popular file formats for audio up to DSD128 and 32bit/384kHz files.
The accessories included are:
1 USB type A to micro cable
1 USB micro to micro OTG cable
1 USB  micro to USB A OTG cable
1 rubber mat
The specs:

Body Material[Design]

Aluminium[Slim] 7.9T

Dimensons[mm) [T.B.D]



80g [T.B.D]

Battery Capacity

1,750mAh / 3.7V[T.B.D]

Playing Time



XS1-U8A-64 (XMOS)


Sabre32 ES9018K2M (32bit DAC)


1.2 ohm


1.9Vrms(No Load)

S/N Ratio[T.B.D]

113dB @ 1kHz


124dB @ 1KHz


0.008% @ 1kHz,


20Hz~20KHz (0.03dB)

USB Input Interface

USB AUDIO 2.0 / 1.0 , asyncchronous

Supported Audio Formats

                                           up to 32bit / 384KHz PCM
Native DSD
DSD over PCM(DoP)
DSD64 (2.8224MHz), DSD128 (5.6448MHz)
Sample rate :
44.1KHz, 48KHz, 88.2KHz,96KHz, 176.4KHz,
192KHz, 358.2KHz, 384KHz


DC JACK-IN (5V/1.2A)



Supported O/S

Windows XP/Vista/ 7/8.1, Mac OS x10.6.4 or later, Android(4.4 or above), iOS7/8/9



I’ve used the Opus #11 a lot for the last couple of weeks and my unit has played for well over 100 hours.
Demo list:
Mark Knopfler – Sailing to Philadelphia
Røyksopp (Feat.Susanne Sundfør) – Save Me
Ane Brun – These Days
Michael Jackson – Dirty Diana
Metallica – Die Die My Darling
The Peter Malick Group – Immigrant
Eva Cassidy – Songbird
Thomas Dybdahl – A Lovestory
Norah Jones – Don’t Know Why
Celldweller – Unshakeable
Jack Johnson – Better Together
Seinabo Sey – Younger (Kygo remix)
Dire Straits- So Far Away
Björk - Moon
Lupe Fiasco - Deliver
Morrissey – Earth Is the Loneliest Planet
Sound impression:
The first thing that I noticed when I started to listen to the bit Opus #11 was how smooth, creamy and relaxed it was while still maintain excellent detail retrieval.
Bass extension and quality is good with no noticeable roll off in the lowest frequencies and good quality through the whole bass spectrum. Mid- and upper-bass is equally great and doesn’t add anything that shouldn’t be there as a matter of fact I find the higher bass to be a tiny bit subdued. This helps giving the #11 its relaxed and laidback presentation, in some ways reminding me of the Mojo but to a lesser extent on the #11 (this is from memory since I no longer have the Mojo around for a direct comparison. The Opus #11 still manage to retain a good drive with all of my IEM’s/headphones while I found the Mojo to lack energy in some (few) pairings.
The laidback sound continues in the mid-range that’s very creamy and relaxed while still sounding very natural and highly enjoyable. This combined with good timbre and great feeling of space between vocals and instrument makes a great sounding signature that continues in the upper frequencies as well. The treble does also feel natural, smooth and airy (albeit not as airy as on the Mojo, again from memory).
The overall presentation has good soundstage in all directions and layering is also good as is the amount of air between instruments. The laidback sound gives a sense of very good separation and black background. Overall resolution and detail retrieval is good but still loses out to some of the top portable offerings I’ve heard, but these are also 2-3 times the price of the #11. That being said this is not something that I notice when listening to the Opus #11 alone but only revealed when doing direct comparison and really concentrating on it.
Please note that the comments in the comparison section are not in absolute terms but in comparison between subject A and B. This means (as an example) that if subject A is found to be brighter than subject B it does not necessarily mean that subject A is bright sounding in absolute terms. I hope this makes sense.
In these comparisons I’ve been listening through my Hifiman HE400i’s.
I’ve been using the USB input when doing these comparisons. Both units have been hooked up to two different Android phones with the same settings and I use UAPP as my player of choice.
Burson Audio Conductor V2+ (1,499) vs the bit Opus #11:
The Conductor V2+ is my reference unit and although it may not be the obvious thing to compare the #11 with I’m including it in all my comparisons section for the sake of consistency.
Compared to the Opus #11 the V2+ has a pretty similar overall presentation. The V2+ has a touch more weight in the lower regions while the #11 is more relaxed in its overall presentation. The V2+ also sounds a bit more analog and natural as well as offering an even blacker background. Furthermore the V2+ also offers slightly better micro details and a more natural and distinct treble presentation. In all theV2+ feels more effortless in everything it does.
The Burson of course has a lot of other advantages such as significantly higher power output (4W @32Ohms compared to the 125mW on the Opus #11, more inputs (both coaxial and optical as well as two analog inputs in addition the USB input) and outputs. The advantage for the #11 is the smaller size and internal battery making it a great portable solution.
Both have a little background hiss but the Burson has even more than the Opus #11.
Of course the area of use for these two is widely different but I still found it interesting to see how they compare in sound.
Burson Audio Air ($499) vs the bit Opus #11:
The Air and the #11 actually also share quite a bit I their overall tonality. Biggest difference is that the Air has slightly more dynamics, making the presentation have more drive from it. The #11 on the other hand feels a bit calmer and, once again, more relaxed with more air between instruments. The Air is also a bit more distinct in its presentation while micro details and timbre is similar on both.
The #11 is a good deal thinner than the Air and makes for a slimmer pairing with a phone.
None of the runs particularly hot but the Air can get slightly warmer in comparison but it also has significantly more power.
The Air has a physical volume control as well as a remote control in addition to a display showing what volume you’re using while all volume control for the Opus #11 is done on the source. The #11 has only a 3.5 mm headphone output while the Air has a dedicated 3.5mm pre-amp output in addition to the headphone output. The Air also has a separate USB micro power input while the dedicated power input on the #11 is a standard 5v input.  The #11 also offers an internal battery while the Air is dependent of power from the source or an external power supply.
Both have a little background hiss, the Air actually slightly more, but it’s still low enough on both to only be audible with my most easy to drive IEM’s.
iBasso D14 “Bushmaster” ($249) vs the bit Opus #11:
These two units are at the same price point. The D14 is an excellent unit offering great flexibility and versatility with all its connections and settings in comparison to the more minimalistic #11 but how do they compare when it comes to sound?
Compared to the #11 the D14 has less bas presence and sounds leaner. The #11 has a bit more air between instruments and a fuller more creamy overall presentation. Detail retrieval is quite similar on both. The #11 does also have noticeable more timbre to the notes making it sound overall a bit more natural while the D14 is slightly thinner and brighter sounding without ever being harsh.   
Like I’ve already mentioned the D14 offers a lot more connections and a gain setting making it more easy to use with a wider variety of sources and IEM’s/headphones while the Opus #11 is a lot more portable. The D14 also offers an analogue volume control while the volume on the #11 must be set I the digital domain.
Both have very slight amount of background hiss and it’s low enough to only be audible with my most easy to drive IEM’s.
The #11 runs slightly hotter than the D14.
LH Labs Geek Out V2+ Infinity ($649) vs the bit Opus #11:
Although I’ve recently compared these two in my review of the V2+ Infinity they’ve got so similar kin of real life usage that I like to repeat it here as well. For those of you who have read my review on the V2+ Infinity this will be pretty much identical. For this reason I’ve chosen to add this comparison I addition the three others that I usually do.
They’re both very slim and have an internal battery making them equally great when paired with a phone. When it comes to sound they both have a similar amount of bass presence but the V2+ bass is a bit more controlled. Overall impression is that the #11 is a bit more smooth and relaxed while the V2+ is more distinct in its presentation. Detail retrieval is equally excellent on both as is dynamics.  I’d say that the #11 is a bit more digital sounding while the V2+ sounds more analog.
The #11 is even a bit smaller than the V2+ making it even better suited for portable usage, especially if paired with a phone. Apart from this the V2+ offers a separate USB charging port, three different filters and gain settings as well as a physical on/off button. It does also offer a balanced output. The #11 on the other hand turns on/off automatically when you insert or pull out the headphones. Both offer an internal battery with about similar battery life.
None of them runs particular hot when being used.
Both have very slight amount of background hiss and it’s low enough to only be audible with my most easy to drive IEM’s.4
For even further comparisons feel free to visit this thread for breakdown between more $250+ amp/DAC units (this is a work in progress and several other units will follow in the near future).
The output impedance of the headphone out on the  is rated to a quite low 1.2Ohm which should be low enough for it to work well pretty much all kind headphones and even very sensitive IEM’s.
In this section I’ve tested how some of my favorite headphones but also one earbud and one pair of IEM’s pairs up with the Opus #11.  
AKG Q701 ($300):
The Q’s pairs up really nice with the Opus #11. The overall presentation with this combo is creamy, smooth and highly detailed. I’m really not missing much from the Q’s here compared to when they’re paired with a lot more expensive sources.
Philips Fidelio X2 ($300):
The X2’s are quite easy to drive but does certainly scale with a good source and are revealing enough to show the difference in sources. The laid back and relaxed presentation on the Opus #11 suits the full and warm characteristic of the X2’s surprisingly well. It makes the X2 sound smooth, detailed and highly enjoyable, in total a great pairing to my ears.
Hifiman HE400i ($449):
Pairing the HE400i with the Opus #11 worked better than I expected. Just like with the Q701 there’s more volume available when reaching a satisfying listening level.  The relaxed, smooth and creamy sound from the #11 makes the overall sound with these two together very nice in my opinion.
Aurisonics ASG-1PLUS ($499):
The ASG-1PLUS is an 11Ohm hybrid IEM (1 DD + 1 BA).
The 1PLUS has an overall laid back and relaxed mid-centric presentation and once again I was pleasantly surprised over how good the #11 paired up. I remember when reviewing the Mojo this was a pairing that didn’t suited me at all, with the #11 though I don’t feel that the energy is lacking in the same way here. Although I’ve heard the 1PLUS even better with some more up front units like the Geek Out V2+ and Ressonecence Labs Herus+ the #11 and the 1PLUS still work very well together.
There’s no background whatsoever with the 1 PLUS:
VE Zen 2.0 ($138):
The Zen 2.0 is a 300Ohm earbud that I like a lot and tend to use instead of closed headphones. It’s also a reliable travel partner for me when I stay in hotels and don’t have any full size cans around.
The soft and smooth signature from the Zen 2.0 fares really well with the creamy but yet highly detailed presentation from the Opus #11. Once again I was half expecting this combination to be too laid back but although it is laid back it’s still very enjoyable and extremely non-fatiguing to listen to. The 300Ohm impedance of the Zen 2.0 doesn’t seem to bother the #11 the slightest and there’s volume to spare even at higher listening levels.
To sum up the matching section the signature of the Opus #11 works really well with all the headphones and IEM’s I’ve tried it with. . Background hiss is pretty much non-existing even when paired with my most sensitive IEM’s. It’s also more powerful than the size would suggest but of course there’s a natural limit for how hard to drive headphones it can power.
The bit Opus #11 is a great piece of equipment in my opinion. If you. Like me, are into Android-Fi it’s certainly hard to beat. It has a great form factor (obviously designed to pair nicely with a phone), internal battery that makes battery drain from the source very low, auto on/off when detaching or connecting your headphones and most importantly a great sound.
While I’d still rate the LH Labs Geek Out V2+ Infinity as better for Android-fi it’s, at $649, considerably more expensive and also a good deal larger.
To sum up the bit Opus #11 it’s the best DAC/amp combo I’ve come across for less than $649 (the cost for the V2+ Infinity) if the main purpose is to pair it with your phone or tablet.  It’s also a great sounding device to pair with a laptop or computer which makes it highly versatile. This is an easy recommendation to anyone looking to upgrade the sound from their phone or even replacing their DAP.
Audio Quality: 4.5
Design: 5
Quality: 5
Value: 5
Features: 4
Ahh, OK, thanks. But what about gain control? I'm not seeing so much as a volume knob, let alone any high-low gain switch.
@abm0 You're correct. Unfortunately there's no physical controls on the unit whatsoever. I don't mind for its intended use though but you wouldn't hear me complaign if they've included it either :wink:
Peter, thanks for another great review! Guess Shanling M1 + #11` must6 be a great and lightweight portable combo.
I know it's not purely 'correct' question, but do you think #11 is somehow comparable to Opus's DAPs (1 or 2) purely soundwise?
Pros: Resolution, portability and seamless pairing with android.
Cons: Power output best suited for IEM



I reached out and asked this company to allow me to review this item. It is not free and I paid to have it shipped to me and agreed to pay to ship it back.
**I will offer to buy it as it is outstanding and fits my ANDROID as a DAP lifestyle**
Great review HBB!  i really enjoy your cutting to the essence of the utility of the device, the sound quality of the device, and how it exceeds the value of similar products that are popular now. masterful, enthusiastic review!  thank you!!! 


Hi, I'm really torn between the Opus#11 and Centrance DACport HD as Android-friendly DAC/amps. Both have advantages and disadvantages vs one another, but I have not been able to listen to either. Have you? If you have, how do they compare SQ-wise?
Hi, I'm really torn between the Opus#11 and Centrance DACport HD as Android-friendly DAC/amps. Both have advantages and disadvantages vs one another, but I have not been able to listen to either. Have you? If you have, how do they compare SQ-wise?
I love the #11 smooth with good detail. I don't have any experience with the centrance though. Sorry