Lots of what makes an Esoteric or Levinson DAC expensive has nothing to do with the sound. They are very pretty, and so are the rooms in which their dealers sell them. That said, there is a lot of excellent engineering and good ears designing those products, so I agree they do sound wonderful.
To make good digital you need silent, fast DC power for chip and output, good DAC chip, vibration control, jitter attenuation, output filter (for OS chips) and output amp stage. These basics can cost a lot, or very little. Altmann's approach is to minimize distortion modes wherever possible, and this is done by simplifying the design to the extreme. Battery eliminates all the problems with AC/DC PS. Wood base eliminates the problems with the museum quality metal box. NOS chip eliminates the smoothing filter. Proprietary programmed reciever chip reduces jitter so it doesn't matter what transport or cable you use. Powerful but simple opamp output stage provides perfect load for the DAC and drive for any load following so no high freqs are lost as with many other NOS DAC designs. It is simple and elegant and the sound is proof of the concept of eliminating distortion. The choices also result in drastically lowered price compared to similar performing DAC whose designers have chosen to reduce all these distortion modes in more traditional ways.
I don't need RS232 control, UL Listing, or silk screened cast aluminum faceplate, golden metal spikes, AES/SBU input or balanced connectors in the back. I don't need a local dealer to help me turn it on and collect tax. I can charge the battery once a month by flipping on the charger with a wall switch. It's ugly but my wife doesn't care because my whole stereo is ugly in her eyes. I have compared it to SB analog, previous couple of Scott Nixon DACs (not the very latest) and hometheaterdoc's Oracle transport and DAC and a small handful of CD players including Mike's Cambridge 804, Rega Apollo. Of these the Oracle combo was my favorite, but I still do prefer the ease of NOS sound. The Altmann is the only NOS DAC I have heard that retains the excitement and clarity of high freqs. It is not laid back at all, it is just easy sounding. It just goes into my head without effort. One friend thinks the 2134s are a little edgy, but it doesn't bother me.
When combined with Altmann's BYOB integrated amp using similar design distortion reducing principles, it is a very fun ride for only $2,500 total electronics cost, including battery charger and stock Squeezebox, only IF 10 watts is enough.
Rich