When I select the same sound card device for both decks (rather than using the Default Directsound Device), the crossfade takes over the volume for one deck – why is that?
(A:) Selecting the direct device will force the deck to control the output directly to the card, this means that if both decks are using the same device they will fight for the volume control, If it comes to you using the same soundcard device on both decks, use the Default DirectSound Device – it will allow you to mix the volume levels.