The HA-2 sports excellent digital circuitry and a nearly flawless amplifier.
Its performance is up there with some of the best, driving low ohm loads with ease, no matter the impedance dip, and it has an elegant gain system for driving hungrier cans. I began this review with my ears wrapped around a pair of FitEar MH335s. My iPod’s OS sets the signal level and the HA-2 sets the amp volume. At a volume of 1 (assuming the green indicator light marks the volume setting), the HA-2 is way too loud for me with the iPod’s OS set at 100% for every earphone I own. But below that, the HA-2 slightly favors the right channel. Dropping the OS volume to 50% allows me to set the HA-2’s volume to 2. Perfect balance from both channels occurs around the 1 marker.
Switching to Mr. Speakers Alpha Dog has me moving the iPod volume slider all the way to the right. When paired with any portable headphone, L/R balance is perfect from the first comfortably loud volume setting. And noise is only audible from sensitive earphones.
But my sensitive ears prefer not to move the HA-2’s volume pot above 2 on the pot even when the HA-2 is driving the Alpha Dog. Switching to my personal favourites, the DT880/600 has me moving the volume up by half a stop. That’s it. High gain adds 10-11dB to the signal. But low gain has been enough for every headphone I frequently use, including the impressive MyST IzoPhones-60.
Of course, I am a low-volume music listener. And while it would be remiss of me to not mention that your mileage will vary, I can say that there is enough volume packed in there for pretty much every headphone you will have.
The volume pot is slaved directly to internal DAC functions. The output of the HA-2 may be controlled by its handsome volume pot, but the volume control of the device still controls the signal level heading to the HA-2. It works brilliantly. And that pot is a clean, elegantly functioning pot. It is a pot without noise. And it looks, and functions, very well. Smooth, grippy, and well labelled. It neither sticks out to the side, nor the top. The only things that stick out are the switches with which you will constantly be interacting. And of course, the strange leather skin.
[From Oppo’s HA-2 Knowledge Base:
When an iOS device (iPhone, iPad, iPod Touch) is connected to Input A, the HA-2 informs the iOS device that it has hardware volume control capabilities and maps the iOS device’s software volume control to the HA-2’s internal, 32-bit volume control. Using this method, the iOS device still outputs bit-perfect audio and allows for finer volume control adjustment than what the HA-2’s analog volume control provides on its own, without any degradation of audio fidelity. This is particularly useful with IEMs and other sensitive headphones. ]
Back to sound. There is no perceptible difference in quality of signal between low and hi gain when driving voltage hungry headphones. When driving earphones, hi gain doubles the amount of background noise, which, by the way, is considerable.
The noise from the HA-2’s headphone output is on par with the AK100, though not as high pitched, and therefore, less annoying. But through every sensitive to semi-sensitive earphone out there, the HA-2 will deliver a thin patina of noise to the ear. If you are a low-volume listener that favors earphones, you will notice it. If you are Chase Emory, you won’t. That noise is the HA-2’s only audible downside. And it is inaudible when listening through anything but sensitive earphones.
Besides delivering excellent current to low ohm earphones and good volume to voltage-hungry headphones, the HA-2 delivers a flat frequency response from 20Hz to 20.000Hz. It is slightly forward-tipped, but not aggressive. The bass boost function affects the band between 20-500Hz and boosts bass by 4 – 5 decibels.
Bass resolution is very good and stereo signal is strong and detailed. The HA-2 is a good DAC/amp for the person looking to really get into their music, into the spaces between this and that instrument. And, when the mood strikes, there’s a pretty good bass boost circuit.
Under the hood is the ESS 9018-2M – M indicating that it is the mobile version of the 9018 S, which Oppo debuted in the HA-1 DAC. It is a great chip. And with the exception of background noise, the HA-2 is simply phenomenal for every earphone or headphone in your arsenal.
If only it were easy to use in the pocket, if only had less background noise from its headphone jack, and if only its volume pot achieved balance a bit earlier on, the HA-2 would be THE machine to upset Cypher Labs’s Picollo DAC. In its current form it is perfect for everything but sensitive earphones. It is a DAC for listeners that enjoy reference-quality, flat, and forward sound, that with the flick of a switch can add in a good, round dose of bass.
And, it is too good a device for 300$. It is far more polished, far safer to listen to, and far too fully functional in a price bracket that is generally either stripped down, or ugly, or unwieldy, or forgettable, or downright obnoxious if not strapped to the ugly we-can-build-it-so-we-made-it philosophy that for so long dominated after market portable audio products.
I will be surprised if 2015 draws to a close with a single product impressing me as thoroughly as does the HA-2. While it doesn’t revolutionize how you listen to your music, the HA-2 pushes quality features, safety, and class into a price bracket that has forever lacked anything but good price/performance splits. And most pricier competition simply can’t stand up to the HA-2’s good looks, great typography, nearly flawless performance, and machine quality.
This is a DAC that the market will remember.