Oppo 95 as a transport

We just purchased a NAIM NDX because we want to get into the high resolution music.  Also,we want to no longer use our Bryston CD player.  (for shelf space)  We did purchase a CD ripping machine and we will store some of our CD's electronically, but not all of them.  

So, I purchased a $130 coaxial cable and connected the Oppo and Naim.  The sound is not very good.  I think I hear some ringing in the high end, and overall performance is flat.  Is there something I should do to the Oppo?  Should I just return the Naim, forget about high resolution streaming and place the Bryston back in the system?