I assume you mean you connected all 6 of the DVD's discrete audio output to the 6 discrete preamp inputs on your AV receiver? With this setup, the only way you'll know if you are in digital mode is when the DVD player tells you, because essentially you are now using the DVD player's Dolby/DTS decoder rather than the one in the receiver.

The "digital" connection you talk about provides the same type of interconnect as an optical hookup, except it uses coax instead of fiber.

Graham