Using the DDA-100 in my home office set-up and couldn't be happier with it.
I was going to use my Music Hall a25.5 amp and Epos M5 speakers with my Mac set up, but realized the amp was far too big for a desktop setup. So started looking at the DAA-100 and the Wadia 151. I finally went with NuForce. After setting it up with the M5 speakers, it just keeps getting better and better.
I just listened to one of my favorite tracks, Van Morrison - Astral Weeks, and was completely stunned by what I heard. It added an incredible delineation to an acoustic guitar that had never really stood out before. It almost sounded like some had laid an extra instrument track over the original song. This is a song/album I've listened to for years and this amp just made it sound new again; putting my main system to shame in the process.
The quality of the DDA-100 far exceeds the price point. If you consider how well it plays, the simplicity and beautiful design of the unit; it really is a steal. Spending anymore on a desktop system would be an exercise in futility.