OPPO HA-2

Introduction –

Like Xiaomi, Oppo leverage their smartphone mass manufacturing prowess to produce interesting takes on conventional technologies. The AMP/DAC market is an interesting field in that it is simply so diverse. As with many users, my first DAC was the Fiio Q1, a solidly built, well performing device and I was content with it in all aspects. But that was until I heard the Chord Mojo, a completely proprietary device that illuminated acoustic intricacies like no other. But whilst Fiio and Chord provide two very impressive devices at opposing extremities of budget, Oppo bring a new contender with their larger economy of scale and design expertise.

Meet the HA-2, a luxury DAC/AMP that promises seamless smartphone integration with all the convenience of a consumer product but the sonic finesse of an audiophile system. With an RRP of $450 AUD, the HA-2 lies right in the middle between the Fiio E17K and Chord Mojo; but does its performance live up to Oppo’s reputation (earned by their renowned PM headphones) and can the HA-2 compete in a market so honed from years of audio experience, let’s find out.

 

About Me – Some background, Gear of choice, Preferences and Biases

I generally prefer a slight v-shape to my sound, but still closer to neutral. I like a lot of detail and clarity, but can appreciate a smooth, laid back sound such as that on the X10`s. I prefer a more neutral midrange within a relatively tight tolerance, but I`m probably more forgiving of brightness over darkness. I`m not particularly treble sensitive and can tolerate large amounts without fatigue, though too much ruins the enjoyment. If I use a different eartip/pad/cover during the review I will note that and describe the sound changes.

Read More

 

Accessories –

Starting with the packaging, Oppo certainly doesn’t disappoint with a very professional design whose darker theme contrasts to the brighter palette assumed by Fiio.








Bold renders adorn the front and right side whilst concise infographics line the left; Oppo also provide a comprehensive list of specifications on the rear.

As one would expect from a manufacturer such as Oppo, it’s similar to unboxing a premium smartphone, which is to say, a very visually impactful experience on a whole.

Like the PM3, the HA-2 lies safely packaged within a hard shell within the display box. Lifting off the top panel users will find the accessories:

1. Manual
2. Warranty papers
3. 5mm Interconnect
4. OTG cable (Android)
5. USB A to Lightning cable (IOS)
6. Two stacking bands
7. Micro B charging cable
8. 5A Oppo VOOC AC Fast Charger

It only takes a glance to notice that the HA-2 ships with a very comprehensive list of extras, the most notable perhaps being the charger which is all too often omitted. The quality of these accessories is what you would expect for $450, the cables are well molded and pliable and the stacking bands are even pre-formed to the dimensions of the HA-2 (and thus pretty much any ~5” smartphone). Attention to detail is key here and Oppo certainly delivers.

 

Design –

The HA-2 makes quite the first impression; the impeccably assembled, leather clad aluminum chassis has the nuance and ergonomics of any flagship smartphone. The subtle chamfers that adorn each edge and the slight countersinking of each port convey the level of thought that went into designing the HA-2.

Whilst some question the leather wrapping (glued on, stitches are for aesthetic purposes only), it does prevent scratching both the HA-2 and your smart device. The leather also provides a really nice feel in the hand, the supple feedback and texture contrasting to the cool metal. As I learnt the hard way, the leather provides just a hint of shock absorption should you drop the heavier device.

Moving onto the aluminum body, the HA-2 is roughly similar in size to the Fiio e18 but is a little slimmer. It`s substantially larger than the E17K and Q1 however (comparison photos below). The interfaces follow an intuitive pattern with the inputs and input switch on the bottom and the headphone and line out ports located on top. The HA-2 communicates through a USB-A or micro-b port when using both the inbuilt DAC and AMP, but accepts a line-in signal through the line-out port when functioning purely as an AMP.

The micro-b port also doubles as the charging port and supports Oppo’s proprietary VOOC fast charging technology. Combined with the potent 5A wall adapter, the HA-2 managed to top off in just over an hour. From full, used as both a DAC and AMP, Oppo claims around 7 hours of batterylife. I managed to scrape 7 hours and 20 minutes in my uses which is good but not great; the E17K offered twice the batterylife whilst the more expensive Chord Mojo produced about the same performance. One feature I did appreciate on the Fiio DACs was the option to toggle USB charging. Since the HA-2 has no such option, it simply charges off any source. This is fine when playing off a laptop or PC but when used with my aging HTC M8, the battery drains quite quickly with no option to use the internal cell of the HA-2 (the HA-2 only charges devices through the USB-A port not the micro-b port). Unlike Fiio DACs, when used with a PC, Oppo also requires the user to download a driver prior to use, but once the driver is installed, the HA-2 is plug and play.

The USB-A port is perhaps the most convenient aspect of the device. The HA-2 has a camera connection kit built-in, allowing it to accept a digital input from all apple devices using only a conventional USB cable, omitting the use of an adapter. It also allows the HA-2 to function as an external power bank, charging devices from its in-built 3000mah battery (@500mah). The source switch allows users to toggle between the three inputs, A, B and C corresponding to USB-A, Micro B and Line-in ports respectively.

The HA-2 has a smooth analogue volume pot with a very grippy texture. Despite this, the pot is still relatively difficult to rotate, reducing accidental volume changes during transit. The pot doubles as the power switch, much like the Fiio Q1 with super clicky feedback. Both channels are also well balanced above 1 of 5 volume notches which will be the useable range for the vast majority of users.

The right side of the HA-2 houses the 4 LEDs that denote remaining charge, a button to activate said LEDs in addition to two switches that toggle low/high gain and bass boost. I appreciate how the battery meter functions even when the device is off. Holding the button enables power bank functionality and an additional blue LED illuminates to denote that the HA-2 is charging your device. I do enjoy the congruency between Oppo’s colour choices with matching pastel green denoting power and charge, it contrasts quite nicely to the black and silver.

So that pretty much sums up the HA-2, it’s a very nicely designed product that is perfectly actualized by strong manufacturing processes. Whereas even the nicely built Fiio e17k has a few defects and limitations with its build, such as slight flex to the chassis and the plastic volume wheel, the HA-2 leverages Oppo’s manufacturing power to create a very discrete device.

 

Sound –

Utilizing the renowned Saber ES 9018-K2M DAC chip along with an AB amplifier, the HA-2 produces a very clean, detailed sound combined with plentiful output current for a portable amp. The HA-2 also supports a huge array of files and sampling frequencies though I won’t detail them all here. You can see the specifications and supported file types below:

One aspect of sound that tends to change significantly as you head into higher end gear is the soundstage. While the Fiio E17K already had a pretty good soundstage, overall, the HA-2 sounds much more spacious, especially when the track calls for it. Plugged up to my Sennheiser ie800`s, the HA-2 feeds them with hyper accurate imaging and a very broad sense of space. The Saber DAC produces superb instrument separation with fantastic timbre and resolution. The large soundstage of the HA-2 is perhaps one of the main reasons it pairs so well to the Oppo PM3, a generally more intimate sounding headphone.

As for the AMP section, the HA-2 produces a very slight background hiss with my UM 50 Pro’s and Shozy Cygnus but not my ie800’s or Oppo PM3`s. There’s a similar amount of noise as the E17K but it’s a lower frequency hiss that`s less distracting. Both aren’t really noticeable when music is playing and I have to concentrate to hear it. With sensitive monitors, there is a noticeable increase in noise when switching to high gain but users shouldn`t find any issues with high gain for more insensitive headphones. For all effective purposes, the HA-2 is essentially silent. The HA-2 has no troubles driving any of my gear, though admittedly I don`t have anything particularly difficult to drive. The HA-2 does offer plenty of current for lower impedance gear and I can`t approach top volume even on low gain, I use about 1 and a half to 2 of the 5 volume steps.

 

Comparisons – 

At 3x the price, the HA-2 offers large performance gains over the Fiio E17K but the differences are still a lot more nuanced than those you would get by upgrading your earphone/headphone. Starting with the tonality, the HA-2 carries the typical crisp and clear Saber sound whilst the E17K carries Fiio’s warmer house sound. As a result, the E17k produces a slightly fuller low end and a darker midrange. Despite this, sub-bass seems more extended on the HA-2 and bass notes in general are tighter with more resolution. The HA-2 also reveals a more refined mid and high end response. Treble notes in particular sound smoother and less crunchy than the E17K whilst resolving a higher amount of detail. The E17K on behalf of its darker midrange does have a more “isolated” treble response which can appear more defined on first listen, but prolonged comparison reveals that the HA-2 has the superior response in culmination with a more balanced sound on a whole. Overall, the HA-2 just sounds cleaner and more composed than the E17K. It also helps that the HA-2 has a lower output impedance at 0.5ohms vs 1.1ohms on the E17K making the HA-2 better suited for sensitive multi-armature or hybrid earphones.

What the HA-2 lacks is the flexible eQ system of the E17K which allows it to vastly alter its sound signature. The HA-2 does have a bass boost, which I found to be particularly tasteful giving just a slight bump to the very lowest end, mainly the sub-bass. The bass boost functioned almost identically on my Alessandro MS1’s as the tape mod, creating a much more balanced sound from the more anemic Alessandro’s with bowl pads.

But how does the HA-2 stack up against something a little closer in price such as the Chord Mojo? When I first tested the Mojo, what stood out to me most was the sense of effortless detail and black background. The E17K has great detail and dynamics but lacks this element of refinement. So perhaps the biggest advantage of the HA-2 over the e17K is that it reproduces sound almost as effortlessly as the Mojo for just half the price. Whilst the Mojo is the perfect mix between the lush E17K and the clean HA-2, the Oppo is much closer in performance to the Mojo than it is to the E17K despite being between the two in price. The E17K tends to get a bit overwhelmed when the track gets overly complicated, the Oppo retains composure much like the Mojo.

 

Verdict –

The HA-2 is ultimately a very competitive device. Whilst users perhaps won`t find a particularly substantial upgrade over lower priced DACs from Fiio, the HA-2 nevertheless produces very impressive results, especially at its price. As far as usability goes, the HA-2 excels over almost every competing model with a housing specifically designed for stacking and other more unique features such as the in-built camera connection kit for IOS devices and power bank functionality.

Whilst the HA-2 doesn’t offer groundbreaking proprietary features like the Mojo or a flexible eQ system like the E17K, a thoughtful combination of premium components and meticulous attention to detail create a device with few compromises. The build and functionality are surprisingly well rounded and the HA-2 feels immensely focused. Although the HA-2 is not a cheap device, Oppo make the customer feel as if they`ve gotten their money’s worth.

Accessories – 10/10, Comes with all the cables you could want apart from a 30-pin connector for older Apple devices. Nice stacking bands. Comes with a 5A fast charger and a very low guage charging cable which is a rarity even among $400 smartphones.

Design – 10/10, A great design actualised through perfect manufacturing. Rock solid chassis accented by green LEDs and subtle chamfers. Analogue pot produces no noise and is well weighted. Buttons are super clicky but bass boost and gain switches can be hard to differentiate in the pocket. Powerbank function works well. No option to turn off USB charging is disappointing but can be remedied with the right cable.

Sound Quality – 9.5/10, Largely improved SQ over Fiio DAC’s with a lower output impedance and a more neutral sound signature. Fantastic resolution and sound staging. Top tier detail retrieval whilst remaining composed with impressive refinement. Slight background hiss, brighter earphones can sound slightly overbearing coming from a darker source.

Value – 7.5/10, Still doesn`t meet the outright value of Fiio DAC’s but improved build and sound do somewhat justify the price increase. At the end of the day, the HA-2 is a luxury item but performs like one too.

Overall – 10/10, The low noise level, low output impedance and smooth, well balanced volume control work wonders for sensitive iems whilst offering enough current and voltage in high gain to satisfy larger headphones. Other notable features include the supple authentic leather wrap, superbly machined aluminium body, ultra clean sound and spacious soundstage. The inclusion of VOOC fast charging makes the HA-2 a multi-purpose device, doubling as a decent powerbank. The HA-2 impresses in all aspects.

Thanks for reading! This review was taken from my blog, please have a look for more reviews like this, guides and more:

https://everydaylisteningblog.wordpress.com/2016/09/23/oppo-ha-2-review/

I set out to do a very unfair comparison:  my new Oppo HA-2 from iPhone vs my Desktop of the Schiit Asgard 2 from Optical Modi from iMac 2011.  Both systems driving my fairly new Oppo PM-3, which I love, but didn’t find well-served by my SoundBlaster e5 unless I tinkered quite a bit with its DSP and equalizer.  I found the claimed Oppo goals, and various Head-Fiers enthusiasm, to be well-justified in the Oppo pairing.  Indeed better sound quality than the PM-3 to e5.  So good, I wondered:  how close is this quality in a portable rig to my desktop configuration?
 
While trying to find this out, I learned some things about my gear, both desktop and portable, that made the trouble I took worthwhile.  But the short and sweet news is that this portable rig happily comes extremely close to my desktop rig.  I’m not going to think twice about the quality I can get in any chair in the house or any walk-about with the portable Oppo rig.  While occasionally there’s a distinction that justifies the existence of the desktop, there’s plenty of emotional satisfaction from the quality of the portable rig.
 
But only if I get all the settings right. 
 
In the first three comparisons below, the Oppo portable rig actually outperformed my Desktop rig.  That didn’t seem right.  Now, when I take the test of 6 tracks in the NPR test of “Can you hear a difference between file formats?” I only score 3 or 4 of 6.  I usually avoid the 128 kbps  file, but have trouble between WAV and 320 kbps.  I don’t consider my hearing “file sensitive” past the current Apple streaming at 256 kbps, and my plan is to shift my budget of music acquisition to streaming Apple Music.
 
But...it turns out that some of my favorite tracks, being favorites, were ripped early and consequently at 192 kbps mp3.  So the first accidentally happy news is that my gear now allows me to distinguish qualities that I had, to date, overlooked or could not detect at all.  My gear has caught up with my ears!
 
OK, after some re-encoding (much more to go!) the comparisons are now truly unfair, but “real world.”  Portable rig at 256 kbps AAC streaming (via home network) vs Desktop rig at Apple Lossless quality. One more caveat:  because the Oppo HA-2 “releases” the iPhone after a certain time, volume level-matching by ear has to occur at almost every comparison.  This really dilutes the scientific method, folks.  When I’ve felt I was hearing something different, I often tried again at slightly different volume to see if the distinction persisted.
 
So, here’s the question of the day:  If, for “serious listening," I take my portable to the living “comfy chair” instead of at the home office Desktop, what kind of quality am I giving up, if any?  Time to compare tracks.
 
Telarc’s all-digital recording of "In The Mood," Glenn Miller Orchestra
     Desktop: Excellent bite to the brass.  The bass is a bit undefined, as I’ve always heard it on my speakers.  Sax trade-off section is produced to be very L-R, but later the centered trumpet adds a sense of soundstage rather than old-timey “stereo” (a la early Beatles).  The trumpet solo shifts from pealing to growling are well-displayed.
     iPhone:  A bit more spaciousness; the bass definition is more clean but perhaps not as deep;  No difference in L-R placement of saxes.   The cymbals perhaps a bit less crisp.
 
Pat Metheny & Lyle Mays, “Ozark”.
     - iPhone:  Lyle Mays’ piano urgency in the upper treble is authoritative and compelling, as if your father had just urged you to do a better job, live up to your potential.  The incessant clicking of percussion marks time raggedly, breathlessly.
     - Desktop:  Conveys more of the beauty of Mays’ playing, as though the edge of the treble notes were not quite as harsh.  None of the urgency is lost.  
 
Manhattan Transfer “To You"
     iPhone:  Wonderful melding of voices who nonetheless maintain individual characters.  Beautiful climb in the piano, etched.  Wonderful lingering to the voices.  Bass swoop not overly defined. Alan’s solo handsomely modulated.
     Desktop: The comparison is so close I had to go back to play one particular passage near the opening.  Perhaps the desktop renders the soprano’s peak of “very” in the line “my very heart and soul,” with a bit more verve, but hearing this is so dependent on a match in overall volume level that I can’t be sure.  
 
Timothy Nolan, “Sorry-Grateful” on Sondheim 2-disc (out of print0  
     - iPhone:  Captures every modulation of the male voice, presents it all beautifully.
     - Desktop:  Difference too subtle to rule out volume imbalance.
 
Ahmad Jamal, “Poinciana” on Digital Works. 
     - Desktop:  In the heyday of the CD, I’d bring Digital Works as one of my “test albums” when hunting for an upgrade to my speakers.  Every shop’s manager would ask me to show them the album for their own acquisition.  Surely the playing excellent, the recording superbly intimate in detail yet with enough sonic “room” around each of the trio instruments to make you feel in the room. Tellingly the bass dives deep just as the cymbals ting delicately while Jamal’s piano zooms from subtle to sparkling to thundering.  Few better tests of your system and my desktop system does it justice.
     - iPhone:  Surprisingly and happily close to the desktop:  captures the interplay of cymbal, bass at subterranean levels and crystal-clear close-miked piano.  Exciting on any system, but the Oppo combo stopped me from all else to listen carefully once again. 
 
The Who, “Slip Kid"
     - iPhone:  After the big bass drum thunders, the count is down, the Townsend guitar must slash, my friends, just slash.  “I’ve got my KIT bag, my HEAVY boots, gonna run ‘till my feet are raw” from Daltrey must have the proper grit and inflection.  This is my anger song and it has to be right.  Hmm, on the portable rig not quite right, on the first try. 
 
HERE’s the 2nd LESSON:  I changed the setting on the HA-2 to “high” and re-matched the volume levels.  Much better, IMO and to my surprise.  Seems the “low” setting affects more than simply volume.  (The HA-2 volume knob is analog-driven when the phone is set to max volume, as mine was.)  The relationship of treble clarity to midrange changes also, and on High it is closer to my desktop reference - wonderful clarity to the slash without sacrificing the bass drum thump.  Now I truly had difficulty distinguishing the systems. 
 
So I went back to listen to “Ozark” once again, and can report that Mays’ piano trilled closer to its truth as I know it from desktop and speaker system.
 
CONCLUSIONS:
 
     - As my gear has improved, I’m better able to appreciate the distinctions between higher vs lower kbps files.  Perhaps you’d benefit from re-visting your older file rips, too.
     - The “high” setting on an amp can be a bit more of a pain in that its harder to make fine volume adjustments, but for the HA-2 (at least), the better sound may be at the High setting.
     - With the right settings and file types, the Oppo HA-2 & Oppo PM-3 combo can deliver a sound quality experience so close to Desktop (at my level), that I will find listening anywhere fully satisfying.  If you’re young, you may take that for granted.  I’ve lived through 8-tracks, mid-fi vinyl rigs, and cassette decks that were increasingly better but not near ‘nuff.  I can tell you:  this is a wonderful time to be a walk-about audiophile.  Enjoy!
 
ADDENDUM - Other HA-2 considerations
 
Before you rush out to acquire the Oppo HA-2 based on my effusing here, check out other reviews.  The HA-2 isn’t that helpful when you get a phone call on your iPhone.  As far as I can tell, it needs to be unplugged from the lightning jack so you can take the call “normally”.  The Sound Blaster e5 has it beat in that regard.
 
Also, the HA-2 is a wonderful pairing with the Oppo PM-3 (as we’d hope) but I’m not yet sure it is the go-to amp for other headphones.  My first quick listens on my Grado RS-1 and Momentum On-ear on the HA-2 were not pairings that immediately seemed “right”.  If I learn more about that later I’ll post it on the HA-2 thread.
 
Thanks.

One of the best amps i have owned! It is great and must have for portable audiophiles~! I love it. It has 2 gain levels high and low. Very nice natural sound! If you feel your headphones do not supply enough bass, the Oppo ha-2 can fix that with its bass boost! The bass boost is nice when listening to some really heavy music. The Oppo Ha-2 has to be the best bass boost i have heard. It maintains the natural sound with no variation of distoretion. Really blew me off my feet when i tried it. This is a steal. The big brother desk amp uses the same chip as the oppo ha-2. So to get it for 900$ off is just amazing! I love it and i can not recommend this enough. I looked for portable amps for months and this stole my heart! I use this with my HD 650's. It has a volume nob on it which will not turn in your pocket i have tried everything and it just does not turn unless you do it yourself. It charges fast and lasts for hours like 8 to 10 hours of constant music! It supports apple, andriod, and of course the jack option. Everything was just very well done! I love the way it looks and feels and this is a steal for $300!

Introduction
I have been looking for a solution to my music problem, I enjoy listening to music and always have but I have struggled to get a portable setup together that gives me a great listening experience without too many compromises. It all started with with my Technics SE-HD70 Hi-Fi system from the 90’s which I still use today as I love the sound signature it gives. I then went into the iPod era with Apple’s AAC Files, from there I went into MP3 320Kbps and CD Quality FLAC with the iBasso DX50. From here I ventured into Hi-Res, then got a Fiio X5 and now ended up with the Oppo HA-2 & My Note 4.
 
Now that we have the introduction out of the way, let us move onwards into this review.
 
Packaging
The packaging and presentation of the HA-2 is fantastic, as you would expect from Oppo. Once you open the box you are presented with the device straight away in all its leather and metal glory. After that you can remove the tray to reveal the user manual, warranty and cables.
 
The cables that are included are as follows:

1. USB to Micro-B, this is for charging the device or connecting to a PC
2. Micro-B to Micro-B, this is for connecting the HA-2 to a Android Device
3. USB to Lightning, this is for connecting the HA-2 to a Apple Device with the Lightning Connector

 
Also included:

1. Wall Plug, can be used in conjunction with the USB to Micro-B cable to charge the device.
2. Two rubber bands to attach the HA-2 to a device such as a phone

 
Build & Use
The build of the HA-2 is second to none, the entire chassis of the device is made from what looks like a solid piece of aluminium with chamfered edges. There is a leather like material which wraps the front, side and back of the device, which also have white stitching.
 
The buttons and switches feel great with a nice deal of force needed to activate them and great tactile feedback. The volume is is very well made, with a nice textured pattern to allow for easier grip. I do wish though that there were additional hardware buttons on the side for the volume because it does make it hard to operate the volume while the device is laying down on a table or in your pocket.
 
Overall the build is fantastic and the use of the product, while the volume control could be a little better, is still great.
 
Sound
This is where things get really interesting. Let us first talk about how the HA-2 get’s on in general with music playback.
 
Setup:
Samsung Note 4 (Snapdragon) 128GB Micro SD Card
USB Audio Player PRO (Variable Output Sample Rate)
Micro-B to Micro-B OTG Cable
Oppo HA-2
Fidue A83
 
Files:
.mp3 320 Kbps
.flac 24-Bit/96 Khz
.flac 24-Bit/88.2 Khz
 
Bass:
The bass from Oppo HA-2 is outstanding, it has an amazing sense of punch with a very strong impact but it is never muddy or distorted. No matter how hard to bass hits, which is always dependant on the track you are listening to where by a bass heavy track like Hip/Hop or R&B hits with authority but tracks from Heavy Metal have a nice hit where you can hear the kick drum but it isn’t overpowering. Listening to an all R&B Instrumental album, the bass has amazing impact and the extension is fantastic. With Fidue A83 which can extend down to 9Hz, you can’t hear but more feel it with the Oppo HA-2 and this album, it is just amazing.
 
Mids:
The mids are neutral in my opinion, they have great detail and a nice spaciousness to them but they are not forward in anyway. While this can be a good thing, in some cases the vocals can get a little lost in some tracks, but the vocals never get forgotten as they are always there and have amazing detail.
 
Treble:
The treble on the HA-2 has great extension and great detail without going too bright or harsh, while with some not so greatly recorded albums the treble will start to feel harsh and sibilant, with well recorded albums the treble is bright but not harsh with a great deal of detail.
 
Soundstage:
The soundstage had a great deal depth, it was wide and spacious but it obviously ain't like an open back headphone. The imaging was well done but the HA-2, the positioning of the vocals, drums and guitars was spot on giving you great listening experience where nothing is really overlapping each other.
 
The Bad
Ok so what I don’t like at the moment:
 

1. The battery life, while it is long, 7 Hours of usage via the Digital input is going to get exhausted especially if you want to use this for a whole day or are travelling on plane for example.
2. Background noise; There is background noise, it is audible but it is only a thin layer. The noise seems to only be present thought when the device is connected with Sensitive IEM’s such as my Fidue A83 which are 11 Ohm and have a sensitivity of 104 dB. There are IEM’s that don’t have such a low impedance as the Fidue A83, such as Noble Audio range which have around 30/35 Ohm impedance. The noise is not noticeable while playing music.
3. The volume control in my honest opinion could be a little better. In the configuration I have it in, most of the time I need to pick up the stack to adjust the volume. So it would of been nice to seem some physical hardware buttons on the side of the device.

 
Final Thoughts
Overall I love the HA-2, it just gives me that musical experience that I was yearning for and after so many years I have it. Now I will be trying to get my hands on some new IEM’s or maybe the Oppo PM-3’s. I do recommend this to anyone who wants to get an amazing musical experience from their Apple or Android device.
 
Thank you all for reading!

You probably already know OPPO as a smartphone brand, but the company called OPPO Digital isn’t exactly the same. It is the American sister company of the Chinese smartphone company, and its main business is Blu-ray player. Recent years however, the company also begins to develop a series of personal audio products including desktop headphone amp and a few planar magnetic headphones, which are very well received by the audiophiles’ community. The HA-2 we are going to look at is the company’s first portable amp + DAC and as the title of this article already suggested – quite an outstanding piece of kit.
 

 
Spec
Frequency Response: 20 Hz - 200 kHz
Audio-in Level: 1Vrms
Line-out Level: 1Vrms
Recommended Headphone Impedance: 16 Ohm - 300 Ohm
Maximum Output Power: 300mW @ 16 Ohm, 220mW @ 32 Ohm, 30mW @ 300 Ohm
Headphone-out Output Impedance: 0.5 Ohm
Output: 3.5mm Headphone-out, 3.5mm Line-out
Input:
Analog: 3.5 mm stereo audio-in
Digital:  
USB A for iPod / iPhone / iPad;
USB micro-B for smartphones with USB OTG feature and computers.
DAC Chip: ESS Sabre32 Reference ES9018-K2M
Input Format: Stereo PCM, Stereo DSD (DoP v1.1 or native)
PCM Sampling Frequencies: 44.1 kHz - 384 kHz, 16 / 24 / 32-bit
DSD Sampling Frequencies: 2.8224 MHz (DSD64), 5.6448 MHz (DSD128), 11.2896 MHz (DSD256, native mode only)
Battery type: 3000mAh Li-Po Rechargeable
Battery Life: Approx. 13 hours (Audio-in) or 7 hours (Digital-in)
Dimensions (W x H x D): 2.7 x 5.375 x 0.5 inches, 68 x 137 x 12 mm
Weight: 6.2 oz, 175 grams
 

 

 
Build Quality
Right off the bat, the packaging of HA-2 already screams premier quality. It almost feels like you just got a top-of-the-line smartphone rather than a portable amp+DAC. The actual build quality is of course just as good as what the packaging has suggested. While I already told you that OPPO smartphone and OPPO Digital isn’t the same company, the HA-2 sure looks like it shared some of the smartphone’s gene on how well it is designed and put together. There is no rough corner anywhere and most of the housing is covered in real leather. I have seen and owned some great portable amp and DAC in my life, but HA-2 has the best build quality so far. It is the portable amp+DAC that won’t make you look geeky when it sits next to your smartphone / iPod / iPhone.
 
As far as accessories go, HA-2 comes with just about everything you need to enjoy your music. All you need is to supply the compatible source and a pair of headphone. In the box, you will find the OPPO’s VOOC Flash charger (which is similar but not identical to Qualcomm Quick Charge on how it functions), the VOOC compatible USB cable, two rubber bands, a 3.5mm-to-3.5mm interconnecting cable, a Lightning-to-USB-A OTG cable for Apple devices and a micro-to-micro USB OTG cable for Android device.
 

ABC switch for input: A for iDevice, B for PC and Android, C for analog audio-in.
 

Gain switch, bass boost, and battery button.
 

The 3.5mm analog audio-in socket also double as line-out when used with digital source.
 
Battery Life
The actually battery life is pretty close to the quoted number by OPPO, which is roughly 13 hours as amp only or 7 hours as amp+DAC, gives or takes an hour or so depends on the volume and headphone you used. Battery capacity can be checked by a single quick press to the battery button on the side.
 
A few things to note: First, if you are using an Android smartphone as source and not planning to use the stock micro-to-micro USB cable, you need to find a compatible cable in order to stop HA-2 from draining your smartphone battery. What you want is a bi-directional micro-to-micro USB OTG cable, not a one-way OTG cable (which is an older standard and rarer these days, but you can still find it). Secondly, HA-2 can be used as a power bank to charge your digital source, mainly smartphone and iDevices, by pressing and holding the battery button until the battery LED lights up. You can use this even when you are listening to music on HA-2, which will keep your digital source’s battery top up as much as it can, but also shorten HA-2 battery life noticeably.
 
Gain, Hiss and EMI
There are two gain setting on the side of HA-2. The lower gain setting is actually a negative gain of about -2dB, where the high gain setting is about +8dB. We will discuss further on this in the SQ section.
 
Hiss performance is quite excellent. Even with my hiss prone Shure SE530, there is no noticeable hiss to speak of with maxed out volume on both high and low gain. Same can be said to click and pop performance, which is barely noticeable. EMI performance is also great. The black ground stays pretty much pitch black with no interference from a smartphone receiving call sitting next to it.
 

Size comparison (from left): Sony Xperia Z2, HA-2, FiiO E12A.
 

Sony A10 digitally feeding the HA-2
 
Sound Quality
As usual, we begin with a look into HA-2’s measurement. RMAA shows an impressive result that just about rival my reference iFi iDAC + O2 setup. Frequency response is pretty much flat, as you can see on the FR graph below. While intermodulation distortion is slightly higher in comparison, it is still well within the inaudible range and doesn’t pose any concern. Used as amp+DAC, line-out is about 0.98Vrms, pretty close to the official number of 1Vrms. Headphone-out on the other hand is about 0.77Vrms max in low gain and 2.52Vrms max in high gain. That’s plenty for IEM and sensitive headphone, but might not push enough volume to really demanding big can. Current output is quite good as well. Not the biggest I have ever measured but it is definitely some of the best.
 
As far as I can tell, the gain factor (-2dB and +8dB) doesn’t change when HA-2 is used as amp only, but it might run out of voltage swing and start clipping if the input is too high. For example, with FiiO X5II’s line-out (~1.55Vrms) as well as iFi iDAC (~2Vrms), HA-2’s max headphone-out on high gain can only push to around 3Vrms, or about +6dB. But interesting enough is that even with such a hot input, the headphone-out doesn’t seems to sound distorted when used in lower volume with IEM. That suggests the clipping isn’t happened on the input but on the output stage. So although OPPO only recommend the audio-in to be used with 1Vrms source (Apple?), it seems okay with other higher voltage input as well. Just don’t expect it to pump out a lot of volume.
 
Output impedance is a bit tricky to measure on HA-2 as it seems to automatically mute the headphone-out when there is no load (*which is needed for the procedure). But judging simply from the tiny voltage drop of two different resistance load, it is obvious the output impedance must be very small and indirectly confirm the OPPO number of 0.5ohm.
 

 
Subjectively, HA-2 also sounds great. The line-out has the characteristic high level of transparency that the ESS Sabre DAC is famous for, but without being too dry or ‘digital sounding’. The headphone amp section itself is also very transparent and neutral. As a standalone amp, HA-2 is very comparable to my FiiO E12DIY, which has been specifically tuned for maximum transparency. I’ll say E12DIY might have better rendering of 3D space, but HA-2 does have an airier presentation. Beyond those, I’ll say HA-2 stands shoulder to shoulder with E12DIY as one of the best sounding portable amps I have heard, regardless of price. One option to spice thing up just a little bit is the bass boost - which really is more of a mild sub-bass boost rather than a full-on rock-your-socks-off bass boost. It gives a bit more substance to the lower range but I doubt it will be enough for any hardcore bass lover.
 
Needless to say, the transparency of the amp section goes quite well with the transparency of the ESS Sabre DAC. Together they create one of the cleanest sounding portable amp+DAC I have ever heard. While I still prefer iFi Audio micro iDSD as a whole when it comes to amp+DAC because of the extra tuning feature on micro iDSD as well as the more musical Burr-Brown DAC’s sound, I think HA-2 does come very close as the 2^nd best. In some ways, especially if you are just looking for a clean sound, HA-2 might even be considered better. Same can be said if you are looking for a smaller devices or with wider / simpler smartphone compatibility. Even as a pure portable amp, HA-2 might have an edge over the slightly drier micro iDSD’s amp section. Metaphorically speaking, micro iDSD is more like a big cannon that can level everything you want while HA-2 is more like a sniper rifle that is better on a specific target. One thing they are equally good is their huge value for money factor, where the choice is really down to how you like to use your rig – as more of a generalist or a specialist.
 

iPod nano 5G feeding HA-2
 

iPod nano 7G feeding HA-2
 
Extra
Here are some extra notes that don’t fit in elsewhere:
 
DSD playback is pretty good on the HA-2, but with a small limitation that it can only do DSD256 in ‘native mode’, which means it is Windows and ASIO driver only and you can’t playback DSD256 on Android, even with app such as USB Audio Player Pro or Onkyo HF Player. In contrast, micro iDSD has no such issue. While I am not actually much of a DSD listener, I think it will still be great if there is a way to solve this.
 
OTG compatibility is really one of HA-2’s greatest feature. Besides being able to be used as a pure portable amp as well as an amp/DAC for PC (*requires software driver), HA-2 can also be used with most Apple devices with its MFi certification and many Android smartphone that supports USB OTG. On the iDevices’s side of things, I have not only paired HA-2 with iPod nano 7G successfully, but also the much older iPod nano 5G, which is not on the official HA-2’s support list. It is not hard to imagine how HA-2 can breathe some new life into older iPod and really transform them to audiophile grade player. On the Android’s side of things is, as usual, a bit hit or miss depends on whether your particular smartphone model will work for HA-2 or not. Based on my own experience, I know Sony Xperia Z series is probably one of the best bet for getting the best sound quality over an amp/DAC because Sony has implemented really good USB DAC driver in their version of Android and they support 24/192 by default. Even without a native USB DAC driver, apps such as USB Audio Player Pro or Onkyo HF Player might still work, though you’ll have to try them out personally to find out. Last but not least is the surprise OTG compatibility of Sony A10 series digital Walkman with HA-2, though the right cable is needed in order for them to work together. That however can be buy from Taobao or Amazon. With A10 as the digital source and HA-2 as the amp+DAC, the A10 really goes from just a decent sounding DAP to one of the best portable ‘audio stack’ around. This setup will really worthwhile if you are like me - which usually doesn’t like to use smartphone as digital source, but doesn’t mind carrying around a ‘stack’. Plus, the stack isn't that big anyway.
 
Those of you who prefer to build your own HA-2 cable for Sony A10 can find a DIY guide here.
 
Sum-up
I remember that the first MFi certified DAC for iPod I have ever read about had a price tag higher than the iPod itself, and it didn’t even have an amp section. Now we have the HA-2 - MFi certified with a quality amp section and Android smartphone compatible, priced only at US$299. While time does usually lower the price of tech, HA-2 still presents some incredible value - especially since most of the competition are still much higher priced. It is a gem, and no two way about it.
 
A thanks for OPPO Digital for the review loaner.

---

Before I start my review, I would like to Thank Oppo US for providing me with a review sample in exchange for my honest opinion.
 
The official product page is here: http://www.oppodigital.com/headphone-amplifier-ha-2/

---

 
I have been preaching in a number of my portable amplifier reviews that many people get these amps for a wrong reason.  Instead of using them with high impedance cans (or earbuds), or driving low sensitivity and less efficient headphones, or applying them to extend battery life of your source (lowering source volume while boosting amp) – people want their portable audio setup to look cool with a small amplifier strapped to the back of a DAP or a smartphone.  When it comes to Oppo latest HA-2 portable amp – forget about anything I said, and just look for any excuse to use this slick little audio gadget!!!
 
In my recently published PM-3 review (HERE), I referred to these latest Oppo products as a “dynamic duo” because their synergy is fantastic.  But it would be a one-trick-pony to use only for that functionality.  When you look at HA-2 spec, you can see it’s not only a portable headphone amplifier, but also a high quality ESS Sabre Reference DAC compatible with PCs and MACs, and USB OTG DAC compatible with Android phones, as well as iOS.  Plus, in addition to having a high capacity battery for its own internal power up, it can be used as external battery charger for your smartphone.  The list of features and technical spec behind it is very impressive, but just like with PM-3 – design details overshadow everything.  Now, before anybody jumps into conclusion that I’m shallow when it comes to audio gear, let me go into a more detailed write-up to describe the brains behind this beauty.
 
Unlike a formally dressed gift box packaging found with PM-3, here Oppo changed its strategy with an eye popping 3D artwork on the front and the side.  You also get bold highlights of all the main features, a very detailed spec, and what appears to be a quick start guide describing every port and every supported connection.  The “gift box” is still there, but now it’s wrapped in a packaging sleeve with all this info on the cover.  I think the idea of such quick-start guide is really interesting where you don’t have to go digging for manuals and can just look it up fast by flipping over the packaging box.
 
Once the box is out of the sleeve and the cover it off, you can see a tray with leather wrapped HA-2 and a brushed aluminum top with a volume pot.  Underneath of this tray you will find documentation and the wall charger with another flap under documentation to reveal included cables.  This particular unboxing experience is nothing short of unpacking a…  smartphone!  You get a smartphone shaped super-slim HA-2, a wall charger and cables – no surprises here since Oppo is also behind a lineup of popular smartphones.
 
Unboxing.
 
  
 
  
 
  
 
Looking closer into the included accessories you will find a wall charger with a heavy duty premium (low gauge wire) cable, a short LO 3.5mm to 3.5mm audio interconnect for an analog audio input from a source, a digital micro-usb to micro-usb OTG short cable for a direct connection to Android phones, a full size usb to lightning connection for iPhone/iPad, and a pair of rubber bands to strap HA-2 to your source.  USB OTG cable is great and very convenient to use without a need for OTG adapters, but I wish they would include one with right angle connectors.  Just think about it, usb connection is at the bottom while HO is at the top, so when smartphone/HA-2 stack is in your pocket it will be sitting on the cable/connector.  Though right angle usb otg cables are available on eBay (just ordered one now), I wish Oppo would offer a shorter version of their own which I’m sure will be a higher quality.  Since I have Apple-free household, I didn’t test lightning cable but aware this one doesn’t require a camera kit.
 
So how about that wall charger and a stiff usb cable?  This is a great example of tech collaboration under Oppo umbrella.  VOOC rapid charge technology was already introduced in Oppo smartphones where it’s backward compatible to source a typical 5V @2A power or accelerated charging with 5V @5A in devices that support it.  Though the industry standard now is leaning more toward Qualcomm QC2.0 for rapid smartphone charging where output voltage switches to 9V or 12V depending on the device, Oppo is pushing their own standard.  VOOC rapid charger cuts down time significantly where HA-2 3000 mAh battery gets charged fully in 90min, but HA-2 is still backward compatible to use with any smartphone 5V/2A charger.  To support high current, HA-2 usb cable uses low gauge thicker wire and a custom crafted micro-usb connector.  The only negative here is once you get spoiled by its fast charging and if something breaks, you have to buy genuine Oppo replacement, since I wouldn’t trust anything else from ebay.  But like I said, it’s not a showstopper because it’s backward compatible with any standard charger.
 
Accessories.
 
  
 
  
 

 
Moving on to a design, I can’t help but to continue using “smartphone” reference in HA-2 description, undeniably with iPhone inspiration.  With dimensions of 68 x 137 x 12 mm and at 175g this is definitely in a territory of slim smartphone footprint.  The first thing you notice when looking at HA-2 is the leather-wrapped exterior with a neat white stitching around it.  Obviously, the leather material is not stitched to a metal, but it creates a premium effect and a feeling of an expensive gear in your hand.  You probably going to call me crazy, but I have mixed feelings about the leather.  It looks like a million bucks in standalone application, and you don’t have to worry about your DAP rubbing against HA-2 surface, but it also means that you can’t apply Velcro to the back or to apply re-usable 3M double-sided sticky strips.  I love the look of HA-2 wrapped in leather, but a part of me wants to feel an even thinner and lighter all brushed aluminum surface of this amp/DAC.
 
Leather wrap aside, all the controls occupy the top, the bottom, and one open side of this device.  At the top you have a shared Line Out and Audio In 3.5mm port, and Headphone Out 3.5mm port.  Everything is clearly labeled and has a letter code next to the port (more about it later).  In the corner recessed you will find an analog volume potentiometer with a nice turn resistance preventing from accidental volume bump, while still allowing turning it with a swipe of a thumb.  As you twist to turn it on, you are greeted with a soft green led light to indicate the power on and to give you some visual of the level in the dark.  This knob is part of a dual volume control where the volume in ESS Sabra DAC gets mapped to a digital volume of your device and you can further adjust it with a pot to give you more control.
 
On a side you have H/L Gain switch, where High gain is capable of driving 300mW into 16 ohm load, while switching to Low gain will be more appropriate for sensitive IEMs.  Between gain setting and dual volume control, you have a lot of flexibility to drive nearly every type of headphones.  Before I go any further, I have to talk about one feature which I haven't seen anywhere else.  Gain switch has a volume mute/fade-in functionality which is simply BRILLIANT!!!  How many times have you switched from low to high gain while forgetting to turn down the volume?  Here after the switch you get a short sound mute followed by a fade in effect to slightly delay a full blast of high gain power - just enough to give you a few seconds to react by either turning the volume down or ripping those headphones off your head.  Hard to imagine nobody else thought of something like this before.
 
Above gain control you have Bass boost which affects both sub-bass and miss-bass frequencies.  This worked great with EL-8C headphones to warm up their sound, but was a bit overwhelming with PM-3, unless you are a certified basshead.  Either way, it’s an option to experiment with different headphones.  Even so I’m fully Android vested, I do know these Gain and Bass boost sliding switches have a lot of resemblance with iPhone volume/mute button.  Above the switches you have a power check button which triggers 4 green led segments (in 25% increments) to show the battery health.  If you press and hold it down, it will trigger to lit up the fifth blue led to start charging externally connected device.  Battery life is quite impressive with 12+ hours of use as analog amp and almost 7 hours of use as a digital DAC/amp.
 
The bottom of the device has full size usb port labeled with “A” (for Apple) where you attach cable with lightning connector tip to pair up with your iOS devices, and micro-usb port with “B” label for USB OTG cable for your Android phone pair up or connection to PC/MAC for use as USB DAC.  For the reference, Audio In on the top had “C” label, while Line Out has A/B label indicating DAC output from either your smartphone or computer digital audio sources.  All this ties up to A/B/C switch located at the bottom which selects functionality and input/output of HA-2.  If you want to connect to Apple device, switch to A and connect corresponding cable to A-port.  If you want Android or USB DAC functionality – switch it to B-port.  If you want a straight analog in/out amplifier – switch it to C.  It takes a few minutes to get used to it, and afterwards it becomes second nature.
 
I just wish there would be an implementation of transport control buttons to Play/Pause and Skip, similar to A200p or E18.
 
Design.
 
  
 
  
 
  
 
Once I got familiar with all the ports, controls, switches, I couldn’t wait to pair it up with my Galaxy Note 4.  There is no need for any USB OTG adapter to connect to your smartphone; using the included short micro-usb to micro-usb cable is all that needed to connect HA-2.  I assume the cable already has internally shorted (pin 4 to pin 5) connection to enable OTG host interface on your phone.  As I mentioned before, my only wish here is to have right angle connectors to avoid arching of the cable and making it more uncomfortable when placing in your pocket.  Other than that, everything worked flawlessly and I had a dual volume control to adjust from my phone and from HA-2 volume knob.
 
While you can drive PM-3 from my Galaxy Note 4, there is not enough power to drive it with authority to bring Oppo planar magnetic headphones sound to their full potential.  Paired up with HA-2, I found bass to sound more articulate, tighter, especially mid-bass being faster and punchier.  Mids sound improved with more clarity and better retrieval of details, and I also noticed an improvement in treble extension with more airiness in sound.  Direct connection of PM-3 to Note 4 is convenient since I don’t need to carry an external DAC/amp, but once you hear how much better PM-3 sounds with HA-2 – there is no going back.
 
Keep in mind, while paired up with your smartphone, HA-2 should be drawing its power from the internal battery rather than your phone.  And if your phone is running low on juice you can use HA-2 to charge it up.  Just attach full size USB to port A while selecting A-port switch, and hold'n'press Power check button until blue led light turns on - now you are ready to charge your phone!
 
Smartphone pair-up/charging.
 
  
 
In addition to pair up with a smartphone, HA-2 can also be used as an external usb audio interface with your laptop/PC/MAC.  To get it recognized, you do need to install drivers for your machine by visiting and following directions in: http://oppodigital.com/headphone-amplifier-ha-2/headphone-amplifier-HA-2-Support.aspx - keep in mind, only Windows users need to install the driver, while no driver is required to use with MAC and obviously no additional driver requires for iOS or Android.  Once drivers are installed, HA-2 was recognized right away BUT it only worked from USB2.0 port of my ThinkPad T430s w/Win7, USB3.0 port wasn’t recognized.  I found this limitation with a few other usb DACs I tested in the past, so just want others to be aware of it.
 
With a digital input, from either your computer USB port or smartphone micro-usb port, sound is being processed through a mobile version of ESS Sabre 32bit Reference ES9018-K2M DAC.  This particular DAC is advanced enough to support PCM sampling frequencies of 44.1 kHz to 384 kHz, with a bit depth of 16/24/32-bits, and also DSD sampling frequencies of 2.8224 MHz (DSD64), 5.6448 MHz (DSD128), 11.2896 MHz (DSD256, native mode only).  For some people spec numbers don’t mean much and you just care about end results, but in general a support of all these sampling frequencies up to a high level of lossless format means that a sound is not going to be internally down-sampled, keeping the original bit depth resolution and bandwidth of frequency content.
 
Paired up with my laptop and tested with PM-3, the sound quality improved significantly in comparison to stock HO and built-in audio chip.  I experienced a smooth detailed tight sound with an improved dynamics, and also enjoyed the benefit of external volume control accessible right from HA-2.  In comparison, GeekOut 450 offered a deeper bass extension, more mid-bass punch, slightly less details in mids, and less treble extension (noticeable in slightly reduced airiness).  I was actually a bit surprised that sound quality of GO450 in comparison to HA-2 was a bit less refined and even a touch more veiled when connected to my laptop.  With DragonFly, low end was also a bit elevated, while mids came closer to the level of detail retrieval though a bit darker.  Actually, DF pair up with my laptop and PM-3 was not bad at all, just smoother and warmer in comparison to HA-2.  Last but not least, pair up with FULLA made mid-bass a little more punchier, mids a little darker and smoother, and a little less detailed.  Now keep in mind, all of these USB DACs are among my favorites, and comments above are just to describe a relative difference.
 

 
 
Since I already jumped into sound analysis with my comparison above between different USB DACs and with laptop and smartphone, let me step back and talk more about HA-2 sound quality based on its amplifier section without DAC in the loop (audio input driven from Line Out of my DAPs).  The spec of HA-2 is very impressive with 1 Vrms audio-in and line-out, low HO output impedance of only 0.5 ohms, and being able to drive headphones up to 300 ohms.  Also, output power (per max high gain setting) scales down from 300 mW @ 16 ohm to 220 mW @ 32 ohm and 30 mW @ 300 ohm which was still enough to drive 470 ohm R70x with authority.
 
In my testing I was using Cayin N6 as a Line Out source and noticed a common thread with different headphones where HA-2 was making sound smoother without any added coloration, just smooth and transparent with a noticeable improvement of detail retrieval.  A soundstage width and depth wasn’t significantly affected, just remained average and similar to a source.  Also, I wouldn’t call HA-2 having a perfect 100% black background, and I did hear a little bit of hissing with some of my sensitive IEMs.
 
In my personal experience it’s usually not easy to describe amplifier sound because it’s a function of headphones sound sig and a source driving it.  Instead, it makes sense to describe it in a comparison to other amplifiers using the same source and headphone reference.  That’s what I would like to do in my description below using N6 as a source and comparing HO vs pair up with Cayin C5 amp, FiiO E12A amp, and HA-2.
 
With PM-3:
 
- N6: has less aggressive bass, a bit smoother, clear/detailed mids, treble is moderately extended (thought with some roll off), not as airy.
 
- N6/C5: excellent pair up, deep articulate bass, more clarity/details in mids, a little more airiness in treble, soundstage gets more 3D with improved width/depth, and also improvement in separation and imaging.
 
- N6/E12A: very similar improvement as with C5 (more articulate bass, more clarity and better retrieval of details), but soundstage is not as wide/deep as C5.
 
- N6/HA-2: bass doesn't get deeper, but becomes tighter and more articulate with a better definition. Mids are more detailed but still remain smooth; treble extension improves and becomes a touch more airy.  This is a perfect example of transparent sound improvement without changing the original sound and still showing a step up in detail retrieval.
 
With EL-8C:
 
- N6: bright mid-forward revealing sound, tight punchy bass without too much slam, bright detailed mids with a touch of metallic sheen, great crunchy airy treble.
 
- N6/C5: improved sub-bass extension, more punch in the mid-bass, detailed bright thinner mids, more pronounced mid-forward signature, and improved 3D staging.
 
- N6/E12A: same improvement as C5 minus soundstage expansion.
 
- N6/HA-2: bass is still tight and punchy and a little smoother, no longer sensing a metallic sheen in upper mids, definitely adds smoothness without taking away details.  A bass boost adds more body to a sound, making it more balanced.
 
I found HA-2 to pair up very nicely with planar magnetic headphones, but it worked well with some other headphones in my collection.
 
ATH-R70x - smooth detailed transparent sound, drives these 470 ohm open back cans with an authority and I didn’t even have to switch HA-2 to a high gain.
 
ATH-MSR7 - tightens up the low end, makes upper mids smoother, sound is still detailed but a touch less harsh, a typical HA-2 improvement in making headphones sound smoother.
 
A83 - improves bass extension, and smoothes out upper mids without losing retrieval of details.
 
W60/UMPro50 - tightens the bass and improves retrieval of details in upper mids, while sound remains Westone-smooth.
 
Since I had a few people ask me how does HA-2 compares to A200p (Beyerdynamic rebranded AK10 from Astell & Kern) and FiiO E18, I decided to add a quick write up on this subject.  In a very brief summary, E18 is only compatible with PC (USB DAC) and Android (USB OTG), and it has a similar concept of operation and footprint with the only advantage of having transport control and also cheaper in price.  But HA-2 stands way above it in build quality, ergonomics of design, and a big step up in sound quality with a better DAC and higher quality amp section.  For a non picky audio enthusiast on a budget E18 is perfect with its warmer less detailed signature, and ability to control playback without a need to turn your phone screen on, but if you want a more refined sound and more elegant design – HA-2 has a definite edge over it.  With A200p, sound quality definitely improves, thanks to Wolfson DAC (A&K favorite used in their debut DAPs), but sound to my ears is a little too precise and digital, almost like A200p and E18 are at the opposite spectrums with HA-2 being in the middle.  What I like about A200p is a big volume knob which is great when used as USB DAC with your PC or MAC (just like HA-2 it supports both), and also transport control for playback.  But what I don’t like about it is the odd little box shape – not convenient to attach to the phone, and also proprietary cables.  It comes with your usual micro-usb and apple and usb connectors to attach to the host, but connector going to A200p is proprietary and gets loose easily.  Thus, I still consider HA-2 to be ahead of both, just wish it would have transport control.
 
 
Conclusion.
 
When it comes to HA-2, I was serious when I said you will be looking for any excuse to use this portable DAC/amp even on occasions when you don’t need an amp!  HA-2 offers a unique combination of a fine crafted design with a high quality build, excellent ergonomics of controls including cleverly placed volume pot, and swiss-army knife functionality to use it as USB DAC connected to your PC/MAC or paired up with your iOS/Android phone or used as an external DAC (with Line Out output) or analog standalone portable amplifier.  If that is not enough, you can use it as an external battery to charge your smartphone.  And to top it all, it actually sounds very good with a smooth transparent detailed signature and plenty of juice to drive even some of the most demanding headphones.  One might argue that often people use external amplifier to color/change a sound, and in that regard I found HA-2 to be on a safe side offering more subtle change.  Maybe HA-2 is not the best sounding DAC/amp I ever heard (though definitely in the top), but I can safely say it’s the most versatile and the best looking portable DAC/amp I have tested to date.
 
... and regarding USB OTG right angle cable, here is what I'm talking about:
 
  
 

I am not an audiophile myself, rather a music lover, searching for the holy grail of SQ that repoduces life-like sound out from records
 
Very well done here, feels pretty sturdy, durable. It is definitively heavy. Button and switches feel pretty solid, esp. the volume pot which has a nice texture and feeling of resistance., the cables feel a bit cheap but not a major complaint here as i only use the USB micro-B, the 3.5mm one and that's all. The included rubber bands also feel sturdy, and hold my dap strong into the HA-2 yet no too tightly to press a button on the DAP.
 
I would have liked the leather cover to be removable, but well is a design desicion made by Oppo, but it looks classy with it and i think it eliminates the need for rubber bumper feet.
 
Kudos to Oppo team, unlike the sony PHA-1A which is similarly priced, the HA-2 includes a line in/out, USB-A port for charging and digital IN for iDevices, USB micro-B fro charging the HA-2 itself, charging your android or other gear with micro-B port and digital IN for those devices.
 
It offers a power bank feature as described above it can charge your devices batteries, it did work with my Walkman, i selected the switch to A and plugged my walkman computer cable to it and got it charging. Tough no data transfer for digital audio IN as sony makes a propetiary cable for that, the WMC-NWH10
 
It works with PCs & MACs as an external USB DAC, for windows i had to install the driver, dwnloading the file from Oppo website, installation was pretty straightforward, no hassles like Fiio DACs where yu have to go to windows boot options to disable the signed driver enforcement options.
 
Gear used: NWZ-A17 Walkman with a 128GB MicroSD card made by SanDisk, sony MDR-1R Cans and sony XBA-H3 Hi-res audio earbuds (IEMS), sony VAIO fit multiflip PC 14'' w/Windows 8.1x64
Software used: Sony MediaGO latest build
Music style: Classical from romantic to baroque, medieval, renaissance, classical periods.
File type: FLAC 16/44.1KHz  to 24/192KHz
 
AMP-ONLY SETUP, SONY WALKMAN A17 W/FIIO L5 LOD (POCC CABLE)
 
Dricving both MDR-1R and XBA-H3 had an improvement in all areas, Soundstage remains similar to that of the A17 which is already pretty wide. I have the volume pot on 1 to 3 depending on Gain, so it has plenty of room to drive more power hungry phones.
 
Driving the MDR-1R on L-Gain deifnitively imrpoves that mid.centric soundsignature by adding some bass extension, heard with organ music, detail and clarity (still burning-in) is somehow similar to the A17 which is great. Switching to H-gain definitvely adss the bass extension to subbass, cellos now have this full body, overall they osound more full-bodied and detailed in the bass area, they aren't those "telephone sound quality" anymore.
 
Driving the Bass bloated XBA-H3 was suprising too as i was expecting the worst for these, either more bass or no imporvement at all, Before they sounded so hollow and weird in the A17 and extremely bass heavy on the fiio x3 1st generation.
 
hooking them on the HA-2, tried L-Gaina nd the hollowness was almost gone but still a bit present, couldn0't get mid clarity nor subbass clarity well. Going H-GAIN did the trick, the hollowness is gone for good, midbass bump is leveled and now they sound closer to neutral, like my ultrasones HFI-780, detailed mids now more forward, and nice bass extension to the subbass.
 
DAC + AMP SETUP, USB AUDIO (SET TO 24/192 UPSAMPLING in windows) VAIO fit multiflip USB 3.0, Sony MediaGO
 
The sound qyuality jump is more niticiable here, i geta  wider soundstage, great presentation from both headphones. It's like eharing my music all over again.
MDR-1R similar to the sony A17 experience, nice subbass extension and detailed mids/highs, but this time with more soundstage . drove them on H-gain and L-Gain, again H seems to add more body and "puff-up" the music.
 
XBA-H3 also were the same experience with the A17, byebye midbass bump, sounding close to neutral on H-Gain and a wide stage.
 
 
Solid build, improves headphones and source quality esp when your source has a weak amp section like usually walkmans do and if it has audio signal processing like my VAIO does. I haven't tested with more headphones but with those two pais i have it deserves and i don't feel any hint of buyer's remorse at all

Introduction:
Good Afternoon world of Head-Fi. I'm a long time lurker turned new member recently. I don't usually write in depth reviews, but recently I bought a fun little dac/amp that was so much fun testing with my various headphones, that I figured I might as well do a little write up based on my personal experiences with the Oppo HA-2. This may not be a traditional review in that, I will be focusing more on my experiences with the HA-2 and various headphones. 
 
A little background on myself - I'm 34(M), married, manager in a small broker/export company in So Cal. I've been into music for a long time, but only recently discovered, and gained the ability to afford, the amazing world of quality Hi-Fi gear. I prefer a warm sonic signature, and can most likely be described as a recovering bass addict. I like a more balanced sound now days, but I still love that bass from time to time. 
 
Now that's out of the way, let's get down to business...
 

Photo taken from: www.oppodigital.com. Credit - Oppo Digital. 
 
Unboxing:
I received the HA-2 on 04/06/15 via USPS priority mail directly from Oppo Digital. The retail box was well protected, and pleasantly came undamaged. Now ever since Apple started the "luxury packaging" trend way back when with the first ipods, it's become almost standard to expect any electronic item over $200 to be packaged like it's an expensive piece of jewelry. The packaging for the Oppo HA-2 is no different. The packaging is very nice, and the items are efficiently "Tetris'ed" in, making for a nice and tidy presentation. The HA-2 comes with quite a bit of accessories, and the included usb to lightning, usb A to usb micro B, and mini to mini cables are a nice addition. The only thing that would have made it better would have been right angled cables. 
 
Packaging & Accessories = 9.5/10 
 
Build Quality:
- The unit has a clean, classy, black tie vibe going on, somewhat similar to a Bowers and Wilkins product.
- Build quality is very solid. Feels well built, with a polished fit & finish. 
- Leather wrap is permanently glued on to the body, which makes using an external case very difficult to nearly impossible. 
- The unit is wonderfully thin compared to most other portable dac/amp offerings, and is on par with a Fiio E12.
- The matte finish + polished chamfered edges make for a nice aesthetic touch as well.
- Volume knob is has nice resistance when turning. 
- My one gripe is that the usb and headphone jacks are on opposite sides, causing the cables to protrude on both sides of the unit. 
 
Build Quality = 8/10
 
Initial Impressions:
- My initial impression of the Oppo HA-2 was that it sounded almost neutral with a hint of warmth.
- The power was a significant step up vs the iPod touch 5G that I was using as a source. I'd never dream of being able to drive my HD650's straight from an iPod, but the HA-2 on the "High Gain" mode provided enough extra umph needed to make them sing. 
- As for the the bass boost function, I tried it for a little while, but quickly turned it off, as most of my headphones are already on the dark side to begin with. The added bass, was just too unnatural on an already dark headphone (ie. 90% of my collection). While I think it's a nice feature, it's not for me. 
- There is no distortion as far as I can tell on either high or low gain mode. It gets louder than I can bear, before I can hear any distortion. 
- The DAC is really nice, especially for this price point! You can easily pay more than twice the price for just a DAC of this quality right now.
- The phone charging feature, isn't really needed, nor is it very high capacity, but it is a nice addition anyways. Someone out there may find it to be a key aspect in their decision making process. More power to Oppo for covering that base too. 
 
Sound Quality = 9.5/10
Amplification power = 7.5/10 
Price/Performance = 10/10
 
Impressions with Specific Headphones & IEM's:
 
Shure SE846 w/ Moon Audio Black Dragon cable:
- Normal listening level: HA-2 > low gain, vol level > 3/5, ipod vol > 70%
**(Your milage may vary, so please just use these numbers to mean a "respectable" volume level for most occasions. Not live concert volume levels). 
- SE846 > Blue Filter, stock memory foam tip
- Better imaging & more soundstage vs just the ipod. Volume gets loud enough to liquify your brain if you accidentally flip over to high gain, so always double check before risking your ears. 

 
 
Noble Audio Kaiser 10 custom:
- HA-2 > low gain, vol level 3/5, ipod vol > 60%
- Pure bliss. That is all. 

 
 
HiFiMan HE-400i:
- HA-2 > high gain, vol level > 4/5, ipod vol > 80%
- Added soundstage. The HE-400i used to sound the most intimate of my open backed headphones, but the HA-2 definitely makes them feel more open vs before. 
- Somewhat hard to drive for their impedance rating. Not sure if I'd use it as a portable since it's so hard to drive. 

 
 
Sennheiser HD650 w/ Venus Audio cable: 
- HA-2 > high gain, vol level > 4/5, ipod vol > 70%
- Pleasantly surprised that the HD650's could be driven by this set-up. Not much headroom left to turn up the volume, but it's enough for portable listening indoors. It's not like you're going to take your open back HD650's on the subway or anything... are you? 
- I can't say I really hear any difference. The HD650 already sounded warm and open to begin with. I guess it's just a little more warm and open.  
- A solid option for a portable open back hifi rig. 

 
 
Fostex TH-900:
- HA-2 > low gain, vol level > 4/5, ipod vol > 75%
- Good grief the soundstage! This doesn't act like a closed back headphone.
- The bass is actually a bit lessened with the HA-2 on low bass mode (which is a good thing imo). It makes the TH-900 a better all around performer, vs just a " get your basshead fix" headphone.
- Really nice, great potential for a truly portable summit-fi rig, if you can handle traveling with $1500 headphones. 

 
 
Audeze LCD-3 (classic): 
- HA-2 > high gain, Vol level > 3.5/5, ipod vol > 70%
- Like the HD650, I don't really hear a significant enough change to comment about the sound. They sound great.... but then again, they always sound great. 
- The only real thing to note is that the HA-2 can drive the LCD-3's very well. I can easily get the volume up to past the point of comfort. 

 
 
Bowers & Wilkins P7:
- HA-2 > low gain, vol level > 4/5, ipod vol > 70%
- While you don't necessarily need the Oppo HA-2 for this headphone, the combo is really nice. The P7 sounds more open, and the bass is a bit more controlled (low bass mode).
- Besides my iem's, this is now the combo I will use when I travel. 

 
 
Last but not least.... 
 
Zero Audio Carbo Tenore:
- HA-2 > low gain, vol > 3/5, ipod vol > 60%
- Boom! These $35 usd iem's have never sounded better! The Tenore's are pretty balanced to begin with, so the HA-2 just makes them sound like they are from a much higher category. 
- These are my work out iem's, and I just thought I'd toss them in the mix. You can't beat these for the price, and they are tiny! 

 
 
Well, that's about all for now. I hope you enjoyed the review for what it was worth.
Thanks for reading, and happy listening!