Oppo HA-1 desktop headphone amplifier/DAC

Best known for its high-performance, high-value universal disc players, Oppo has expanded into the high-end headphone and personal audio electronics marketplace. First came the firm’s flagship PM-1 planar-magnetic headphones (reviewed in issue 115 and 116), and now we have the long-awaited HA-1 desktop headphone amplifier/DAC (£1,199), which effectively completes Oppo’s premium headphone system.

The HA-1 borrows analogue and digital audio technologies from the firm’s award-winning BDP-105-series disc players, but then ups the performance ante in several respects. To begin, the HA-1 provides a broader set of digital inputs and two sets of analogue inputs, giving owners outstanding flexibility in source selection.

Also, like the BDP-105D, the DAC section of the Oppo HA-1 is based on the ESS 9018 Sabre32 Reference DAC. This supports PCM formats up to 32-bit/384kHz and DSD files ranging from DSD64 on up to DSD256. The HA-1 is supported native in Mac-based systems, but needs an Oppo-supplied driver set for use in Windows environments.

By design, Oppo’s HA-1 supports a different and somewhat broader set of roles than its disc players. Thus, it can be used as a conventional high-end stereo DAC, as an analogue/digital preamplifier (complete with home theatre bypass), or as a high-powered and full-featured headphone amplifier/DAC sporting both digital and analogue inputs.

The analogue amplifier section of the HA-1 is a fully balanced design, based on discrete Class A circuitry. In exchange for that extra bit of heat Class A brings to the party, listeners enjoy extra precision and clarity, plus all of the high gain/low-noise benefits that fully balanced amplifier circuits confer. Oppo takes an unabashedly purist approach to its balanced circuit topology, emphasising that, “For digital audio, the signal runs in balanced mode all the way from the DAC to the output jacks.” Further, Oppo stresses that the HA-1’s, “balanced analogue input is kept intact, and (the) single-ended input is converted to balanced at the input buffer.” 

The HA-1 provides both a single-ended headphone output (via a 6.35mm headphone jack) and a balanced headphone output (via a 4-pin XLR connector). In balanced mode the amp delivers output of 800 mW @ 600 Ohms or 2000 mW into 32 Ohms, while in single ended mode the amp delivers 200mW @ 600 Ohms or a 500mW @ 32 Ohms. Frequency response is quoted at 10 Hz – 200 kHz (+0B/-1dB) or 20 Hz – 20 kHz (+-/-0.04dB).

Oppo’s HA-1 is offered either in brushed black or silver, with both versions offering the type of upscale anodizing and surface finishes rarely seen in affordable components. It also comes with a lovely, sturdy, and easy to use remote control whose metal-sleeved housing gives it a just-right touch of weight and heft in the hand. Moreover, the HA-1 provides an absolutely beautiful, colour user interface screen that is highly reconfigurable to suit the owner’s tastes.

The display supports basic setup and control functions, enabling users to choose from among digital or analogue inputs, to configure muting options, to select screen dimmer settings, to set fixed or variable DAC output modes, to enable or disable Home Theatre bypass settings, to choose between normal and high gain modes, and to set playback volume levels. Moreover, the HA-1 provides three primary display options: a text-only Settings Summary screen, a real-time bar-graph type Spectrum display, or a display panel that depicts an old-school pair of VU meters. All in all, the display panel adds a welcome touch of polish and class to the HA-1, giving it the look and feel of a considerably more expensive product.

Importantly, the HA-1 comes with a first rate User Manual, which is worth taking time over. Sophisticated multifunction components such as the HA-1 merit a certain amount of study, if only so that owners learn how to take full advantage of the broad range of features and functions they support. In any event, the quality of Oppo’s documentation sets an example I wish more manufacturers would follow.

During my listening tests, I fed the Oppo HA-1 a variety of uncompressed standard and high-res PCM, DXD, and DSD digital audio files from a Lenovo-based music server running jRiver Media Center 19 software. Test headphones included Oppo’s own PM-1s; HiFiMAN’s HE-400i, HE-560, and HE-6; and the Abyss AB-1266. Finally, to assess the HA-1’s capabilities as an analogue/digital preamplifier, I used the HA-1 in my main reference system, where it drove a pair of AURALiC MERAK monoblock amps connected to a set of GoldenEar Triton One loudspeakers.

Considered as a headphone amp/DAC, the HA-1 offers a sound that is articulate, that offers very fine levels of resolution, and whose tonal balance is neutral without becoming ‘clinical’ or sterile. Where some past Oppo products have exhibited tonal balance shaded to a degree toward the colder or brighter-sounding end of the ‘neutrality sweet spot’, the HA-1 really plays things straight up the middle of the tonal balance fairway. This is very important because today’s better headphones are exceedingly revealing and thus tend not to tolerate even trace amounts of excess brightness or sonic sterility very gracefully. Happily, the HA-1’s neutral sound lets the natural warmth of good recordings shine through, producing gorgeous—yet not unduly lush-sounding—results with top-tier headphones.

The only very small caveat I would mention is that, because the amplifier section of the HA-1 features pure Class A circuitry, it is important to allow the unit to come up to full operating temperature before doing critical listening (this takes about a half hour, give or take a bit). This wait-for-warm-up precaution is, as many Hi-Fi+ readers know, pretty much par for the course when using any solid-state Class A audio device. When cold the HA-1 can sound, well, a bit cold and ‘stiff’, but as it warms up it invariably begins to sing quite sweetly.

One interesting aspect of the HA-1 is that its own capabilities seem to expand to match the capabilities of the transducers with which it is used, which I consider one of the hallmarks of fine audio electronics components. For example, if you use the HA-1 with a very good but moderately priced headphone such as HiFiMAN’s excellent HE-400i, the HA-1 will show the HE-400i in a favourable light, enabling the headphone to deliver very good (albeit not quite top-tier) levels of definition, resolution, and finesse. But, if you plug in a headphone with considerably higher performance limits, such as the Abyss AB-1266, the HA-1 unleashes whole new levels of textural refinement, dynamic agility, and sonic subtlety.  After a time, I came to trust the fact that the HA-1 would let me hear all—or nearly all—that even the finest headphones have to offer.

As you might expect, the HA-1 makes a terrific partner for Oppo’s fine PM-1 headphones, serving up more than enough power to drive those headphones up to and beyond sane listening levels. It also has sufficient power to drive very inefficient headphones, provided that you use the HA-1’s balanced outputs, which have considerably more dynamic ‘oomph’ than the single-end outputs do. If you’re the sort of listener who, down deep, prefers a one-stop shopping experience, you could order up a pair of Oppo’s PM-1 headphones (or perhaps the new cost-reduced PM-2 headphones) plus an HA-1 amp/DAC and live quite happily ever after.

However, the really interesting part is what happens when you match up the HA-1 with even higher performance transducers like the Abyss AB-1266.  When you do that, the HA-1 serves up stunning layers of power, subtlety, and finesse, in the process showing that its sonic sophistication belies the unit’s comparatively modest price. This point was driven home to me during a session where I used the HA-1 to power the Abyss AB-1266s as I listened to the powerful and passionate ‘Eat, Drink’ passage from Ståle Kleiberg’s opera David and Bathsheba [2L, high-res DXD]. The passage shows an interchange between King David and Uriah that—with the Oppo’s help—proves to be packed full of vocal power, nuance, and emotion, plus a quality of stage presence so vivid that it nearly takes one’s breath away.

On David and Bathsheba the Oppo waded right in with the suave self-assurance of a much more expensive amp/DAC, letting listeners hear how Uriah is torn between a desire to please his King yet committed to honouring his men by declining the offer of dining with the King. The Oppo/Abyss combination captured, but did not overplay, the complex interplay of emotions revealed in both of the singers’ voices, with the Oppo demonstrating power, nuance, and control comparable to—if not fully the equal of—far more costly components.

But an even bigger surprise came when I inserted the HA-1 at the front end of my reference system. From the outset, it was apparent that the HA-1 was very quiet and that it offered plenty of gain. I heard that same subtle, powerful, self-assured quality that had won me over during my headphone listening sessions. But I also heard one thing more: namely, an unexpected treble delicacy and ‘sweetness’ of the kind no previous Oppo component has been able to achieve in such an effortless way. As a result, the HA-1 found the elusive sweet spot between detail and resolution and graceful musicality of the sort that fosters long-term satisfaction.

Oppo has a long history of building well-respected high-value products, but in my view the HA-1 stands as the firm’s best all-around effort to date. What is impressive is not just the number of roles the HA-1 can play (as a high-performance headphone amp, preamp, and DAC), but the astonishing sonic sophistication that it brings to each of those roles. If you have wanted near benchmark levels of performance for a fraction of what most benchmark components cost, look no further. In the best possible sense of the term, Oppo’s HA-1 represents a true ‘point of diminishing returns’.

Technical Specifications

Type: Solid-state, class A, balanced-output, desktop headphone amplifier/preamplifier with high-resolution DSD and DXD-capable DAC.

Inputs: Digital: Bluetooth with aptX support, one AES/EBU input, two S/PDIF input (one optical, one coaxial), one asynchronous USB, and one mobile USB. Analogue: One stereo single-ended input (via RCA jacks), one balanced input (via XLR connectors).

Outputs: One single-ended headphone output (via 6.35mm headphone jack), one balanced headphone output (via 4-pin XLR connector), one stereo single-ended analogue output (via RCA jacks), and one stereo balanced analogue output (via XLR connectors).Other: 12V trigger signal in/outs.

Device drivers: None required for Mac environments, Oppo-supplied driver pack required for Windows environments.

Supported digital formats and sampling rates:            S/PDIF and AES/EBU: PCM, 44.1 kHz – 192 kHz, 16 – 24-bit.Asynchronous USB: PCM, 44.1 kHz – 384 kHz, 16 – 32-bit; DSD: DSD64, DSD 128, and DSD 256 (native mode only. Mobile USB: PCM, 44.1- 48 kHz, 16-bit

Headphone amp power output: Single-ended: 200 mW @ 600 Ohms, 500 mW @ 32 Ohm, rated power.           Balanced: 800 mW @ 600 Ohms, 2000 mW @ 32 Ohms, rated power. Maximum short-term power output allows generous headroom reserves

THD + Noise: DAC: <0.00056%. Preamp: <0.00071% single-ended, <0.00056% balanced. Headphone Amp: <0.0056% single-ended, < 0.0018% balanced, both figures at rated power.

Signal to Noise: DAC: >113 dB single-ended, >115dB balanced. Preamp: >105 dB single-ended, >110dB balanced. Headphone Amp: >111 dB single-ended and balanced

Dimensions (H x W x D): 80 x 254 x 333mm

Weight: 5.9kg

Price: £1,199

Manufacturer: Oppo Digital UK Ltd.

Tel. (UK): 0845 060 9395

Tel. (Europe): 0044 845 060 9395

URL: www.oppodigital.co.uk