Quote:
Originally Posted by
Nitrooxidus 
They are speakers 2x50 W, game are not important I just need clear sound from the piano, what are your thought on the dac.Thanks.:)
Did a bit of searching - this page might interest ..... http://www.head-fi.org/t/493801/interesting-little-dac-optical-coax-input/30
Gives you one persons perspective on the DAC.
If you're looking for a value amp/dac combo with USB, co-ax and optical input, with gain switch - have a look at the Audio-gd NFB-12. It uses dual Wolfson MW8741s for the DAC. It's really a headphone amp - but I power my Creative T20s (they are powered speakers - but the NFB-12 has both fixed and variable line output) from it. It's a warm sound but can be altered by using switchable digital filter combinations inside the unit.
I think you really need specialised help for your questions though - and might be better asking in the "Dedicated Source Components" forum. You'll get better answers there than I can give.