I might have missed it, are you using the Oppo’s Modwright DAC or an external one? The factory stock DAC in my Oppo 105 is relatively smooth, but a little bass lite and lacks depth, compared to the Ayre Codex. The Ayre has their proprietary digital filter that is as ring free as possible. No pre ring and only 1 cycle of post ring. The analog out put stage has great dynamics and bass power. First song scared the he.. out of me. The Oppo never did that.
The variac didn’t solve all the problem until it was also hooked to the Oppo.
Thanks,
aldnorab