Just Get A Better DAC?

A DDC is a great addition if you want to use a PC for streaming.  If you have a high quality streamer with i2s out... no need for a DDC.

Want a great DAC with a built-in streamer for a reasonable price?

Here is one option.

 To make it even better I would recommend using a pair of fiber media converters to connect it to your network.

Man, to the OP, I appreciate the question.  I've gone to the ends of the Earth on this one.  I spent years tweaking my DAC/Streamer combo with all kinds of enhancements.  I won't lie, I was able to coax some really incredible sound out of it but by the time I was so fed up with it, my wife had name the thing "Medusa" because of all the stuff hanging off of it.  

I sold it all off and spent way too much money on a DAC and streamer combo that utterly blows my mind and nothing I could do to the old system would ever come close.  Sometimes I question my own sanity when I think about how much I've spent but it's all for the love of the music.  Yes, I would most certainly do it again.

@ulmerc 

+1 to this kind of experience. 

Mine has been the same. While you can do incremental improvements to streaming by making your network less noisy... ultimately the best solution is to get a great steamer (with an equivalently good DAC). 

I dont stream. I use only digital format from my computer, then i use many separate  devices that improved all my experience,

These are golden advice, i used jitter control.Clock control. Buffer and filters, then a linear power supply... All this at low cost for my low cost system... Great improvement in S.Q. 

Experience teaches you that the essence of the musicality also resides in the line signal processing stages, the power supplies (transformers, filtering, regulation), and the digital signal processing before conversion, and the quality of the key components: clocks, transistors, op amps, capacitors, etc…