Not that it was bad, it's just the Marantz brought music to life on my system. Vocals were very laid back on the Oppo and the Marantz brought them forward and in my face. Bare in mind this comparison was using the analog out's on both units wired to my Rotel together so I was able to switch to one or the other immediately. Volume levels were matched.
I'm just wondering, how are the differences you heard possible? What you're describing might be due to one of two situations:
1. The DAC in one of the units is grossly non-linear (grossly in the sense of the variations in IC production), and is falsely producing the wrong analog signal levels that corresponds to the value in the sampling data words.
2. The analog line-stage circuitry in one or both units has poor frequency response linearity.
I would argue that the relative probability between the two choices is that (2) is far more likely than (1).
Analog non-linearity can be caused by a variety of factors, from poor circuit design to unfortunate matching between components (and fault could be in a downstream component, the Rotel). So it seems possible (to me), but I've got to say that it seems highly unlikely, and even more unlikely to produce the euphonic or laid-back effects you're describing, which sound like they're frequency range-specific. And from Oppo no less, which is held in high regard by people who measure things.
A long time ago some digital circuits had ringing or other bad effects (often from crude digital filters), or poor-designed discrete line-stage amplifiers. But these days modern IC DACs and IC op-amps are approaching audio signal perfection. Obviously, telling you that you really didn't hear the differences you imagine is futile, I'll leave that to the everything-sounds-alike legion that hangs around here, but the particular effects you're describing are difficult to develop explanations for.