Here's an update.
The Yamaha CR-420 is cleaned up, working good, and sounds great with the Triangle Titus' in my 2nd A/V system.
I'd account for the synergy of the Yamaha with the Triangles as a result of a combination of low distortion that these vintage Yamaha units are known for combined with the re-knowned clarity and detail of the Triangles.
This system sounds the most transparent, clear and detailed at present as it ever had with either prior receivers: a Tandberg TR 2080, which sounded quite sweet in it's own right when I had it, or the NAD 7020 I called into duty to fill in for the Tandberg.
I was never really very pleased with this particular NAD in this system. The sound had a nice warmth and good dynamics, but lacked in clarity and detail, particularly at lower volumes. The Yamaha really shines at lower to moderate listening volumes which is typically how this system is used.
So it looks like the NAD 7020 is probably heading eventually into the system for my boy, whenever that comes to fruition.