I have a DDA-100 which is a DDA-120 minus the analogue input. It must be one of the best bargains in hifi, especially if used in a mainly digital system. Think of it as a power DAC: digital signals are amplified and sent straight to the speakers.
It has ultra low noise levels, very good dynamics and transient attack and a very extended smooth treble. The only downside is the analogue input which falls far short of the digital inputs. I guess the analogue is useful though for those who want to plug in an mp3 player or similar.
Geoff