Review – Oppo HA-1 Headphone Amplifier

When we reviewed the Oppo BDP-105 Reference Audiophile Blu-ray player last year, we noted that it promised a new approach to listening to audio. With its extraordinary analog output section, ESS Sabre DACs, and most excitingly, the combination of a USB-addressable DAC that could be used by your computer system, coupled with a built-in headphone amplifier, it was a device that could take the place of your pre-amp, headphone amp, DAC, and more. In fact, the number of audiophiles who purchased the BD-105 with no intention of taking advantage of its superb video section was a wake-up call to the audio enthusiast market.

In my own testing, I connected a NEC display to it, and used it as a stand-alone music player, utilizing the built-in headphone amplifier. In many ways using the BDP-105 was a revelation, using an external USB hard drive loaded with music that included high-resolution, Redbook, Apple Lossless, AAC, and MP3s, I had no need of a computer, no need to hassle with often-buggy high-resolution music player software and the variables they introduced, and just listened to music. There were limitations of course, it wasn’t easy to create custom playlists, scrolling through music with a remote control isn’t the same as a configuring a playlist of searching through thousands of tracks, and there was no control over EQ if I desired it. But, I loved the simplicity of it. Absolutely no hassle, just plug and play, and it was all about the music. The only serious limitation was the headphone amplifier, which though very competent, was obviously limited by its inclusion into another product as opposed to being the feature the product was designed around.

While Oppo hinted to me that they were well aware what many of their customers were purchasing the BPD-105 for, I wasn’t expecting this full-fledged rethinking of their relationship to audio, which is essentially what the HA-1 represents. By taking some of the best features of the BDP-105, namely the seamless and extraordinary analog audio section, removing the video and optical disc apparatus, expanding the headphone amplifier into a no-compromise pure Class-A design and implementation, and then adding a balanced output and input, USB input for Apple iOS devices, and fully addressable asynchronous USB input, they created not only a new DAC and headphone amplifier, but redefined the market segment.

I first saw the prototype of the HA-1 at CES in January during lunch with Jason Liao of Oppo, Igor Levitsky who was fine-tuning the audio signature of the PM-1 headphones, and our own John Mulhern III. When Jason mentioned they were bringing both the headphones and amplifier to lunch, I envisioned a hand-held amplifier a few pounds in weight, a few inches in size. But when Jason opened the case and slid out the HA-1, we had to clear the table just to make room for it, and we all realized what a substantial design statement it represented.

Unfortunately, it turned out that Jason left the power cord in his room, so we were unable to fire it up right there on the lunch table. It may sound strange, but during CES having an amplifier on a table filled with breadsticks and silverware isn’t as odd as it sounds. Being able to see it in action would have to wait a couple of more days until we reached the Oppo suite, where I was able to hear it paired with the prototype PM-1, which gave me an idea of the level of audio performance Oppo had in mind.

I was fortunate enough to have the PM-1’s to work with for a while, and after about a month of testing, I received word that the HA-1 was on its way to me. I was not expecting a box that seemed large enough for a small refrigerator, a testament to the quality of the packing and the effort put forth to protect the product. Inside was a silver HA-1, providing a retro look especially when used with the digital VU meters. I think that choosing between the black or silver models may prove to be one of the toughest choices a consumer has to make when considering the HA-1. While the black aesthetic seems to be the favorite of audiophiles and photographers alike, the silver model is lovely and understated design-wise, and is a nice counterpoint to the sea of black components.

The HA-1 is very simple to get started with. Most users will probably opt for the USB connection to their computer, and a standard USB port is provided. There are a slew of other options, but I suspect that the majority of folks will use it for high-resolution digital audio. Its digital inputs include coaxial, optical, balanced AES/EBU, and an asynchronous USB DAC that supports PCM audio up to 384 kHz, 32-bit resolution, and DSD audio up to 256x the CD sample rate. It uses the same ESS 9018 Sabre32 Reference DAC and output driving stage used in the OPPO BDP-105 audiophile Blu-ray player that has already earned well-deserved kudos. Hardware-wise there is little that the HA-1 can’t handle.

One other option is the USB port on the front panel, which you might be tempted to use for access to the DAC, but is exclusively designed for use with an Apple iOS device such as an iPad, iPhone, or iPod. This feature allows you to bypass the built-in, low-cost DAC in those devices to gain the superior audio processing of the HA-1. Bluetooth isn’t known for high fidelity, but there are schemes to get around its inherent limitations; the aptX audio CODEC allows high-quality sound from the lowly Bluetooth protocol, which is included with both the Apple iOS and Android 4.0 Ice Cream Sandwich used by the Galaxy SIII. My Galaxy connected on the first try, and within seconds it was playing music through the HA-1, with the display confirming that aptX was present and active, and the sampling rate of the source material. I tested with both an iPad and a Samsung Galaxy SIII phone, and it worked well with both. You can control the HA-1 with the supplied remote control, but also via Oppo’s free app for Android or iOS. These are all features that I think will satisfy any home theater user. While I’m using the HA-1 with a direct connect to a computer and headphones, I can easily imagine that other folks will use it with their home theater system, so the variety of input choices and output control will prove very useful indeed.

As for choosing between the BDP-105 vs. the HA-1, I think they are really different beasts. When I first saw the HA-1 during CES, I kept thinking it was a BDP-105 minus the transport, but after living with it, I’m more than convinced this isn't the case – it is a completely different genus.

For example, the BDP-105 has optical transport, can grab Internet radio, Netflix, etc., and has a superb analog output stage (so does the HA-1) but also has the ability to grab music from a flash drive, or external hard drive. The HA-1 can’t do any of those things, nor does it display graphics. The HA-1 has a full Class A amp of course, which isn't present in the BDP-105, and can drive a far wider variety of headphones with a higher level of fidelity. To navigate the files and sources you need an HDMI-equipped display or TV on the BD-105, while the HA-1 has no such video out capability, so it is wholly dependent upon the source computer, software, or Bluetooth source for operation.

One very cool thing about the BDP-105 aside from its sonic and video excellence is that you can skip a pre-amp or receiver and drive powered speakers directly, or directly to an amplifier. I did this, and loved the audio experience. And I did run Amarra, Decibel, and Pure Music into it as my DAC from both my Mac Pro and Macbook Pro running Snow Leopard, which worked great. By comparison, the HA-1 is a dedicated headphone amp/DAC component, and while it, too, can drive powered speakers, or connect to an amp, it really can't be compared to the BD-105 since it must get source music from somewhere else, such as a computer, Bluetooth, iOS, analog input, or digital source via optical, or co-ax. Still, it can eliminate the pre-amp for a variety of users, and I think that paired directly to the line-level input of an amplifier, or pair of monoblocks that you might just find audio nirvana. Why add a pre-amp if you don't need one? Amarra, for example, has a superb software-based EQ capability, so I found that using Amarra, Pure Music, or Decibel and the HA-1 directly to my amplifier was a stunningly powerful and easy-to-use combination.

Most of the time though, I used it for its primary intended purpose: that of a no-compromise headphone amp and DAC. For headphones I've tried a variety of dynamic models from Audio-Technica, Sennheiser, Etymotic, Ultimate Ears, and Phiaton. In all cases the HA-1 made a significant difference, especially in the richness of depth of the bottom end, over USB DACs, and the built-in output on our Mac computers. So far it can drive everything I've thrown at it without a hiccup. Like any Class A amplifier, it runs warm, but not uncomfortably hot, with the vented top panel screen reminding me to turn it off when not in use. I had no issues with it being recognized by the Mac OS, showing up in System Preferences as soon as it is powered up.

There are two knobs on the unit; the one on the left changes the choice of input, and once selected offers three visual modes, a spectrum analyzer, analog VU meters, and track info. Most of time, I preferred the spectrum analyzer since it provided both an entertaining view and track info, so the best of both worlds, but the VU meters are fun to watch. The knob on the right hand is actually a motor-driven precision volume control. The provided remote control allows for remote volume adjustment while keeping the audio in a pure analog audio path. Whether I turned the knob manually or used the elegant remote control, there was no introduction of noise.

Ultimately, my favorite combination was the Oppo PM-1 with the HA-1. While I’ve enjoyed throwing all my old headphones at it, in the end when I just wanted to relax and listen to music, I relied on the PM-1s. I also tried an early build of the balanced headphone cable, with little or no discernible difference that I could hear so far, although the unit I tested was built with normal OFC copper, rather than the famed OCC copper used in retail build of the balanced cable, as well as the 1/4-inch cable. Using the balanced cable didn't require any changes to the interface – according to Oppo the 4-pin balanced XLR headphone jack does not have any plug-in detection mechanism, they use the plug-in detection of the 6.35mm TRS jack. As a result, the XLR balanced output will be muted when a 6.35mm TRS plug is inserted. I switched between the two, but as much as I thought I could hear a difference, I think it was more imagined than real. The XLR socket has a solid fit, and it’s good to know that the HA-1 comes ready to use with the high-end headphones that rely on balanced output.

While the PM-1s are very efficient, few headphones are that fortunate. However, the HA-1 has adjustable gain to accommodate a wide range of inputs. I wasn't sure what the optimum setting was in software, and both Amarra and Oppo confirmed that setting it to O dB was the best approach. Amarra and other solutions allows you to bypass the gain control with a checkbox, thus insuring bit-for-bit accuracy to the DAC, while other software solutions allow you to just set the volume to O dB of gain. Oppo is working with software vendors to populate a FAQ site with these tips and tricks to get the best performance out of the HA-1.

One of the nicest aspects of the HA-1 is how hassle-free it is in operation. Just turn it on, and it works. Without tubes to warm up, or bias to adjust, it seems destined to provide years of service with nary a thought or tune-up. The more I used it, I began to wonder if it had a sound of its own, although I couldn’t really pin one down. Some amps, especially tube amps, seem to have a unique sound, but the HA-1 seemed to be neutral (although there was a three-dimensional quality that emerged, especially with better headphones and earphones). Compared to USB-powered DACs, the bottom end - not just the lower bass registers, but the lower mid to bottom registers - had a warmth and a believability that seemed effortless.

While I’ve always enjoyed Mumford and Sons’ album Babel, I’ve never thought it particularly well recorded. The various instruments should have their own distinct sonic signatures, but on most systems they blend to a bit of a morass. Even the HD Tracks high-resolution version of Babel didn't entirely eliminate that confusion, but in combination with the HA-1, and the PM-1, I finally felt as if the mix made sense, especially in lifting a bit of the murkiness. In the bonus track featuring Paul Simon and Jerry Douglas on The Boxer, Simon’s voice and Douglas’ Drobo guitar blend to a greater good, with a rich bass line supported without a hint of distortion. Just for fun, I pulled out my vintage Sony DR-Z6 headphones, with their palladium coated drivers. The DR-Z6 were famed almost one-off products built to showcase Sony's new line of then state-of-the-art television and audio line, and despite their cult status among audiophiles, I've always found them to sound like, well, like headphones. Accuarate, fast, and clean, but they always sounded like I had headphones on. Using them with the HA-1, and listening to Babel I can honestly say that for the first time, they didn't sound like headphones, instead the soundstage opened up, and the murky morass of the lower timbre of The Boxer suddenly cleared. When I tried the DR-Z6 with my collection of USB DACs, they were back to being fatiguing and uminpressive. Clearly, they needed the audio heft that the HA-1 provided, which I chalked up to that lovely Class A topology. The lesson is that you should dust off your old headphones and see what they can deliver when paired with the HA-1, you might be surprised, I certainly was.

Joni Mitchell’s recent high-resolution tracks from HD Tracks are a case in point. Using some USB DACs, Ladies of the Canyon seemed to have an edge of sibilance, not quite strident, but a bit wearing on extended listening. With the HA-1, however, the natural vibrato of Mitchell’s voice came across as youth, passion, and sincerity, and reminded me why I fell in love with her work in the first place, ecohed by Blue with its melancholy ache. Jaco Pastorius’ bass lines zoom and boom all over the place in Don Juan’s Reckless Daughter, Hejira, as well as Shadows and Light, and the HA-1 made me acutely aware of the senseless loss his passing represented. The early live album Miles of Aisles, with Tom Scott and the L.A. Express kicks into gear marking the soon to be full-on tranformation of Mitchell's shift from singer-songwriter to jazz and rhythm explorer, with the HD Tracks version coupled with the HA-1 surprising me with the better than expected recording quality of this legendary title. I’ve always looked to bass lines as a guide post for audio performance, since there exists a very fine line between boomy, thumpy bass; bass where you can hear the strings vibrating; and the musicality of the bass as it interacts and informs the rest of the music, and these titles are mindful of the importance of the role played by bass in Mitchell's compositions and performances. 

My son is a bass player, so maybe the years of hearing a real live stand-up acoustic bass in the house, or a Fender Jazz or Precision bass pumping out rhythms have focused my concentration in that area of the musical signature. It has also helped to hear the differences in bass guitar amplifiers and cabinets, opening up an entire world of subtle and not so subtle bass notes. Accordingly, where the HA-1 class A topology seems to really strut its stuff is the lower end, which not only is the bass solid, but believable and textural, and it improved the performance of every headphone or earphone I threw at it.

The Oppo HA-1 headphone amplifier is one of the most versatile audio products I’ve ever used, and at its $1,199 price point I can’t imagine any manufacturer of DACs, Pre-Amps, and headphone amplifiers who shouldn’t be paying strict attention. This is a superb product that we can find no faults whatsoever with, and whose sonics rank among the finest we have heard. It is easy to use, rock solid and stable, built to jewel-like precision, and is incredibly flexible. Oppo clearly has another killer product on its hands, and I imagine that over the next year plenty of households and studios around the country will find an Oppo HA-1 humming away on their desktops. The toughest choice won’t be if you should buy the Oppo HA-1, it’s going to be what color. Highly recommended.

Harris Fogel, with additional reporting by Nancy Burlan, posted 5/29/2014

For more information on the Oppo HA-1 Headphone Amplifier visit:

For more information on the Oppo PM-1 Planar Magnetic Headphones visit:

For more information on Joni Mitchell on HD Tracks  visit:

For more information on Mumford and Sons on HD Tracks  visit:

For more information on Pure Music from Channel D visit:

For more information on Amarra visit:

For more information on Decibel visit: