What's really happening in my receiver?

Situation:
In the process of evaluating the need/want for an SACD player I ended up listening to three different CD players, one was a standard multi-disk player and the other two were SACD players. The SACD players were/are hooked up analog while the standard player is hooked up with both analog and digital cables.

What I've found is that all three players have a similar sound stage using the analog cables, but the standard one hooked up with the digital cable has a very different soundstage. Obviously, whatever is happening in the receiver in digital vs. analog processing is the major difference.

I have an Integra 50.1 that has been running in Direct Mode for all listening. It seems strange that the D/A converter can be totally responsible for the change considering how similar three other players sound, so what else is going on?

I thought the direct mode was supposed to do as little as possible, but seems to be making a significant change.