I just want to say thanks to all who posted your insight and impressions on this thread. Sorry about those who experienced trouble with the A2. I've never seen a site where the manufacturer monitors the posts and responds to answer questions. Well done, Jason.
I purchased the A2/uberB as my first desktop combination about a month ago, before I found and read this thread.
I have experienced zero hum from my A2. Also, it doesn't get very hot but I'm driving low-impedance devices with it.
The A2/B combo provides a big improvement to the sound quality with all my devices. The old setup was simply a computer/dragonfly. I have no experience with other desktop equipment.
In particular, I noticed great improvement to the bass when driving the Shure SE535. The brilliant treble/mids are enhanced but the bass is much better so those IEM's are now a real pleasure to experience.
Other equipment I'm driving with the A2/B are the Ed-8 and LCD-X. I was thinking about selling/trading the Ed-8 until I heard them driven by the A2/B. Now they sound quite good and balanced even less scratchy in the mids. The LCD-X are just a great set of cans and sound extraordinary with the A2/B. On the LCD-X appreciation thread, people are raving about them driven by the balanced Schiit equipment; that may be on my horizon as well.
Overall, well satisfied with the A2/B equipment especially at it's price point.
I particularly wanted to thank those who posted comments about the A2 driving higher impedance cans like the HE500 and HD800. Good to know the A2/B combo will likely drive the HD800 which are on my wish list.
Happy New Year!
All the best -