Thanks for the kind words, akdrama. My player is a Pioneer DV-578A, the cheapest "universal" player (CD, DVD, DVD-A, SACD) I could find at the time I was looking. That was just before I heard of the Oppo units. As I think I've already written, the Pioneer feeds the 990 a digital signal via a Mapleshade Ultrathin coax connector ($42 for 1 meter), so I'm using the 990's DAC (unless I set the 990 to 7.1 input, in which case the Pioneer's DAC feeds the 990's left and right analog inputs). The tube buffer is between the 990 and my Adcom GFA535 power amplifier. That is the only way it can affect all possible audio sources.
As anyone reading this can conclude, I may have champagne tastes but my budget is at the imported beer level.