Where is the weakest link?

What is it that you are trying to improve upon? You do not indicate what your perceived area of weakness is...what is it that you are hearing or not hearing? That may help point in the right direction. Just remember, there is nothing that is perfect. 

Focus i have is cables, i do have a cheap stereo tube preamp that i plan to insert, a schiit freya that i want to replace. I will run chord dac into a tube preamp eventually. Am testing the nad’s stereo playing expertise.  I dont like using a tube preamp in a home theatre system as no one has created a nice high end stereo tube fit that is convenient and is a true ht bypass.

great comments herein, thanks.

no one has created a nice high end stereo tube fit that is convenient and is a true ht bypass.

I believe Rogue, VAC, and Backert make tube pres that may work in bypass mode without tubes glowing so might be worth checking out. 

Anyway, in my system I get the biggest impact from interconnects closer to the source.  I’d start with an Optical Rendu from router to streamer, then I’d replace the Monster with an Acoustic Zen Silver Reference interconnect (balanced if possible) as it’ll preserve all the detail/dimensionality of your DAC without adding etch or bleaching tonality.  I think those two changes will make very meaningful improvements to start.  Hope this helps, and best of luck in your search.  

Thanks soix

No mention about speaker cable?

transparent for use as rca interconnects?

Optical rendu intriguing but another layer?

Talk the Electric Company into putting a transformer on the pole that your house wiring feeds off.  20+ years ago, the local electric company added a transformer on the pole across the street from my house and my wire to my home was connected right after the transformer.  Since then, I get a constant 124 volts from my outlets and all my systems since then sounded much better.  Prior to that my house voltage was always between 117 volts and 120.