Yes. The level that you choose as your baseline isn't that important. The goal is that you equalize all of the speakers to that baseline. I think that most of use use 70, 75, or 80 db. Depends on what you're comfortable with.
Whatever tool you use, whether it's a test DVD or tone generation as a setup function of your receiver, the point is the same. You'll play a test tone through one speaker, perhaps the left front. Then you'll adjust the main volume control to hit a specific db*. Say 75db. Now you'll either go to the next test (on a DVD) or change the tone to the next speaker. Perhaps the center. Now you will NOT use volume knob, but you'll use whatever calibration function that your receiver has to adjust that specific channel level up or down. If it's reading 73db, add 2db of trim. 79db, subtract 4db. You get the idea. And you just do that for every channel in your system.
A sub (including the EP500) really isn't that much different. Your receiver should have a trim level for the sub as well. However, the sub is unique because it will have it's own level control because the sub has its own amp. Usually a knob on the back. There should be recommendations on where to start with the EP500's gain level in the EP500 manual. It's a bit of a balance between how much gain you want to add or subtract from the receiver's trim vs what the EP500's gain will be set to.
For example, if you set the receiver's sub trim level too low, you may send the EP500 too little of a signal to trigger its remote turn on.
*Some receivers, like my Pioneer Elite, automatically set the volume control to a specific point when I tell it I'm calibrating the speakers. In this case, I don't have a choice in what the baseline db reading is. I just match all of my speakers to whatever db is produced by the left-front speaker.
