Oppo 970 sounds better than HDDVD player on DVDs?

Hi all,

I have both an Oppo 970 and RCA HDV5000 HDDVD. I had been using the RCA in the main system to watch both DVDs and HDDVDs, using the digital output into my Sony DA4ES receiver. I was at that time using the Oppo in the bedroom to watch some DVDs on a TV we have back there.

I decided I wanted to put the Oppo in the main system so as to be able to get into some DVD-Audio and SACD listening.

But since I had the Oppo and the HDDVD player connected via component to my Mits TV, I thought I would compare the picture quality on regular DVDs at 480p(the Mits has no HDMI input). It turned out that, at least to my eye, the image quality was a bit better with the Oppo.

But what astounded me was that reciever-decoded 5.1 movie tracks seem clearly superior with the Oppo. The sound is clearer, dialog is more intelligible, musical instruments sound more real, the surround channels are more active, there is more dynamic impact to transients. The movie experience is definitely better with the Oppo.

How can this be? I would have thought both players would be sending the exact same digital stream to the receiver. The only difference is that the Oppo is connected via coaxial cable, while the RCA is connected via glass optical cable. Could the cable differences explain this difference? I have been told that for movie 5.1 audio, it wouldn't matter whether I connect with coaxial or optical.

Any ideas? One thing is for sure. That Oppo is a bargain.