As some here know, I am one of the people who think there can be audible differences between electronic products, especially analog ones. I always listen before I buy, or at least before I lost the option to send it back. The problem is, Ponzio, as others have pointed out, that even if there are measurable differences betweens between the Oppo and Yamaha you don't know that the difference is due to the DACs. And, I wasn't kidding, one of those units could be defective. It happens. Bad caps are a plague these days. If you really and truly hear a night and day difference I'd take them both to a shop and have them bench tested. Of course, brace yourself for them both checking out fine.