Interesting. I would have said just the opposite in general about lower-end Sony DVD players.
That is, to my ears, the audio DACs Sony puts into them don't impress me much. I have a Sony DVP-NC655P changer in my HT setup, and I love the picture quality per dollar spent, but I detest it as a pure CD player. However, I don't really care, because I just use my HT reciever's DAC anyway (Crystal delta-sigmas, I love 'em). But I would definitely not use it as a CD player from the analog outs. In fact, if you look at places like audioreview.com, you'll see this is a common criticism of Sony DVD players in this range.
This may not apply to the higher-end stuff like zeplin's 9000es, I'm not sure.
Obviously, your mileage may vary.