Stephen, I think you made the right decision, as it is very unlikely that any break in effect would get the unit as "...way too bright," down to the level of warmth (lack of "brightness" you want).
"Bright sounding" is somewhat subjective, you know, and there is a continuum from tubby, "chocolate" sound to tight, technical sound. The Cambridge I found to be a pretty good compromise, with an emphasis on detail; yes slightly bright. A lot depends on the associated cabling and components going to the speakers. I am able to reduce what you'd call brightness quite a bit by placing two Digital cables in the system in place of interconnects. This will work in any rig. It's unorthodox, but it does a wonderful job of adding a rich, tube-like sound. The power cords are also very effective in moderating some detail/brightness.
I felt the unit was excellent as a transport and have used it with the Monarchy M24 tube DAC quite effectively. It increased the warmth dramatically, and with Digital cables was even more mellow sounding. I do like the detail that the 840C is capable of, and there are ways to make it less aggressive sounding. One DAC which has a very high degree of the tube sound is the Van Alstine UltraDac.
