Much has been made over the impedance of BNC versus RCA connectors. In my system, an RCA terminated digital cable with so called 75 ohm RCA/BNC Monster adaptors sounded better than 2 BNC terminated cables.
So to me, the issue of what will provide the best sound is not all that clear cut to me. I suspect it depends on the available terminations and design details of each unit, The Monsters adaptors do sound better than the other adaptors I tried (crappy nickel?). Also, the more more metal mass, the longer the terminations may take to settle in. I find XLR, binding posts and BNCs all seem to take longer than RCA.