Just to confirm, you are comparing CDs, not SACDs, right? The Chord would decode the CD layer, while the Oppo could play the SACD layer.
In any event, I don't think you're going nuts, you just prefer your Oppo's sound. While there are differences in DACs, they may not be as great as you would be led to believe, and some of the differences are more sonic "flavorings"--hence the different filter settings on the Chord. Could you find one you liked better than the others?