1st impressions...and remember, although I have an appreciation for high end audio, I do not have a lot of experience with DACs or headphone amps.
I was running out of the house when the FedEx box came and I took a few minutes out to open it, inspect it and hook it up to my Mac in the two channel listening room to see if I could tell the difference. Since I was in a hurry, I was just happy the thing worked at all, so I unplugged it and took it with me...after all, it's a portable DAC!
Some time later while waiting in a somewhat noisy barber shop, I decided to do a little A/B testing between my iPhone 6+ and the HA-2. I didn't have anything high quality preloaded on it, so I went to Spotify, choose "Extreme" for bandwidth and chose a track I was familiar with...British R&B band Incogito's latest album "Amplified Soul", track 2 "I Couldn't Love You More". Incognito's music features excellent vocals, funky bass and usually lots of horns. The first thing I noticed was that the HA-2 was way more precise playing the same music than the iPhone by itself. In fact I was stunned that it was that obvious. The best analogy I can give is that the iPhone's DAC was almost smearing the music, subtly in some places, more obvious in others. Like droplets of water being accidentally spilled on a watercolor painting.
Since I got home, I paid the in-app upgrade for the Onkyo player so I could load all of my HD music onto it (anything 24 bit in my library). One of the standouts is published by Linn Records, "Toccata in Fuque in A minor" recorded by Pavlo Beznosiuk. Most people have heard this very recognizable classic around Halloween played by a pipe organ, usually keyed in D minor. This time it's all violins, violas and maybe a cello. Nothing I had before could quite reproduce the "scritchy scritchy" nature of bows against strings that this recording demands. The Oppo is there all right, and I'm just listening to this through Apple EarPods. Imagine what happens with real headphones!
And this seems to be the reoccurring theme....compressed music sounds less compressed. Redbook CD rips sound more focused and precise. 24 bit music ups the ante again with some of the music getting into that "3D" soundstage that is hard to reproduce properly, especially with cheap EarPods.
Now the HA-2 can't save every recording. One of my all times favorite performances is Diane Shuur and the Count Basie Orchestra with "Deedles Blues". Diane Shuur is at the height of her powers and the beginning of a long distinguished jazz vocalist career, but a 1987 all digital recording is let down by the recording and mastering equipment of the day. Even with the Oppo, the recording sounds a little too strident, too brassy, and not realistic, which is a shame since the recording all but demands you listen to it at full throttle. Only a pre-amp or amp with a nice set of tubes is going to smooth out the rough edges. Still, the Oppo handles this better that anything I've had before and I'll play it on the tube pre-amp in my house at another time.
The same goes for "The Rise and Fall of Paramount Records, Part 1", a masterpiece box set of early American jazz, blues and religious music curated by Jack White and Third Man Records. If you're not listening to all 800 (!!) tracks on LP, then the digital versions are all MP3s at 320 kbits. That's ok since all of the original recordings are from 1917-1928, barely past the wax cylinder days in terms of quality and fidelity. The HA-2 does manage to find some clarity I haven't heard before, mainly from the ability to find some extra precision to compressed music lacking in a standard iPhone or Mac/PC DAC.
More notes...the build quality is awesome....a worthy accessory to my iPhone 6+. But it's also the size of a phone so you wind up carrying two devices to do the job, which is inconvenient but its not like we didn't sign up for this. I fear losing the three cables included with the unit...I need to find a small carrying case that makes sense for everything...I don't want most of this disappearing in the wallows of a backpack. The USB used for charging and Mac/PC USB DAC work has a green marking much like the blue markings on USB 3.0 cables. I'm not sure if this cable is special so far as the fast charging of the unit. The HA-2 does heat up a little when operating but nothing uncomfortable.
Overall, I'm pretty happy with this purchase. It would be nice to follow with some real headphones at some point. It would be nice to be able to audition the PM-3s which match the unit at some point...maybe one of these days.