Audyssey XT Auto EQ Question

I'am going to get a Dennon AVR 2809 CI and I would like to know how Audyssey Works with a sub. Some subs like Velodyne and others come with their own Mic and room set up EQ. With this type of sub would you use this on board EQ first and then let the Audssey in the Dennon do a final EQ? Or just use the Audssey EQ in the Dennon AVR ? I do not yet have a Sub and this will help me decide if it is necessary to get one with onboard EQ or not. Thanks Gary
Either don't use the EQ in the sub at all (save money: buy a sub without it) or use the sub's eq first.