Nothing else changed, unless that particular night they sent me green instead of gray electricity or the other way around. Lunar phases and stellar constellations are beyond my control, too, obviously.
I'm afraid we are not going to find a credible explanation. I have no reason to believe the devices malfunctioned, nor the amp, nor the cd player.
Perception bias? I don't think so. The difference in sound with the old receiver and cd players was too big.
As for the statement that "all amplifiers sound the same " that people seem to propagate here, I am not sure if that is true. I heard a Luxman, a Sony and an Akai. The Luxman and Sony were soundwise very close, the Akai had a warmer, less neutral, (though not muddy) sound.
Perception bias? Maybe. Until now I have seen no big studies, just a test from the eighties with serious methodological flaws and indirect conclusions why all amps should sound the same. I am not saying that is not true, I am just saying there is no good evidence backing that claim (nor is there good evidence for claims stating the contrary).
As for all DAC's producing the same sound: No, that's just nonsense. I cannot distinguish between my old Philips and Akai player listening to them, but my husband's Sony cd player just sounds bad compared to the two other players, and though the Sony receiver's analog sound is good, the digital one isn't.
