It is using advanced ADI DSP chip. Has complete single-chip audio system with a 28-/56-bit audio DSP, ADCs, DACs, and microcontroller-like control interfaces. Signal processing includes equalization, cross-over, bass enhancement, multiband dynamics processing, delay compensation, speaker compensation, and stereo image widening. This processing can be used to compensate for real-world limitations of speakers, amplifiers, and listening environments, providing dramatic improvements in perceived audio quality. Most processing is done in full 56-bit, double precision mode, resulting in very good performance. It is a fully programmable DSP. The easy to use SigmaStudio software allows the user to graphically configure a custom signal processing flow using blocks such as biquad filters, dynamics processors, level controls, and GPIO interface controls.

Long story short. If you use it 2.1 system you can add advanced parametric equalizers and tune subwoofer crossover as you like. Still having USB DAC, headphone amp and power amp included.

If you have big 3 way speakers pair of such devices can fully replace passive crossovers and amplifiers (thing usually done with DCX2496 - http://www.behringer.com/EN/Products/DCX2496.aspx and additional amps).

It is now very widely known product, but this company exist for quite long time already.

• GD33 - http://www.aliexpress.com/item/DSP-CLASS-D-AMP-SMPS-2-1-OR-THREE-WAY-HI-FI-AMP-WITH-ANALOG-SPDIF/522265351.html
• GD22 - http://www.aliexpress.com/store/product/DSP-CLASS-D-AMP-SMPS-2-1-HI-FI-AMP-WITH-ANALOG-SPDIF-USB-SOURCE-SELECTOR/601158_536791086.html