Pros: Astounding quality, both in sound and build. Tons of features.
Cons: Would have liked it slightly less square and more rectangular....full length chassis.
Some first impressions now that I've had the HA-1 for a week.
It's totally natural on the my Beyer DT800/600s. The bass improved over the EMU 1616M I was using previously, which was fully expected. I probably shouldn't have been running a 600Ohm can on that interface, though it did a good job overall. Treble and mids blended well with great distinction on both cans and powered speakers.
Secondly, the soundstage on both the XLR outputs to my powered speakers as well as the cans had a more forward presentation. In fact, I'd say it's where it should be. The EMU really had a recessed soundstage. I like to listen nearfield, and one would think that the forward presentation puts you further into the room, but it doesn't. In fact, the stereo image is nicely presented from only 5 ft away (speakers are about that far apart as well). Vocals are clear, with no overhang or excessive warmth on male or female voices, but both acoustic and electric bass has nice weight along with excellent note delineation. Electric guitars have the rasp one would expect from their originating sound, but are not harsh. If you see or have experienced much live music in your life, you'll be impressed. Finally, I hate saying this since the description seems overused from new equipment reviews, but I really do hear more detail now than I did prior.
Oddly, I bought this as more of a DAC/Preamp than a headphone amp, but I believe it will cause me to rediscover my cans again. This said, it has exceeded my expectations in every aspect. I usually listen to it with the screen dimmed completely off, expecting that there may be some audible benefit, though I haven't heard a difference. I purchased the silver model because I read that the silver anodizing process produces better sound than black. LOL. Kidding of course.
Overall, I couldn't be happier. I can't believe what you can get for under $2k these days.