DAC suggestion Please

You have a $300 pair of speakers that includes amplification.  To my mind, your Zdac already outclasses your speakers.  I think you'll get a much bigger improvement upgrading your speakers at this point.  Best of luck. 

Going up to LS50 actives would be a much better upgrade path, IMO.

I would say that upgrading either the active speakers OR the DAC will give an increase in sound quality.  The KRK Rockit are not bad, and they are at the same level as my Yamaha HS8 (only smaller).  I have been able to make my Yamaha monitors just "sing" by doing DAC/preamp upgrades as well as power cord/fuse upgrades.   Sure, the Kef LS50 are definitely more accurate and high resolution, but the DAC source is important as well.

Thanks for assistance.
End Result
i bought a Chord Qutest for my "big" rig

I upgraded the speakers on my "desk rig" to Fluid Fx8 and am moving the Chord 2Qute to desk.  

@saleh84 Why do you think R2R DAC sound better compared to sigma delta.