The answer is: It depends.

Most mainstream DVD-As are compatible with DVD video players (i.e. those players that don't support DVD-A). In this case, the player outputs through the digital connection to your receiver. You need to carefully check each disc to make sure it supports DD or DTS. Some are DD 2.0 and 5.1. In these cases, you are not getting the high resolution audio from the disc.

When you have a DVD-A player, you need to hook it up with analog interconnects in order to get the high resolution audio. Again depending on the disc, you can select surround (6 channel but not necessarily 5.1) or stereo. One more important note, some discs disable the ability to listen to the DD tracks if the player is capable of playing DVD-A. Warner Brothers is notorious for this.