If you usuallly use a Firewire or USB soundcard, when you launch max without it connected, no ad driver will be selected. Then if you select your built in sound output, next time you connect your external soundcard, you'll have to re-select its driver. This patch specifies a preferred (1st choice) soundcard, and one to use if that is not available (2nd choice). To use it specify your 1st and 2nd choices as arguments (the name needs to be exactly the same as what is repoted by adstatus. Put it in a patch in your maxstartup folder to open automatically when max starts.