I noticed somthing when I had a second ep500 in my house..

The first one going to the reciever was set near min (maybe at the 6-7 oclock position.

The second one I had daisy chained required the gain to be set at a much higher value to provide the same output...
placement was a small factor but I have placed my first sub in both of those locations and there was not that BIG of a difference.

I had sub 1 powered off with the second sub daisy chanied from it when calibrating.. maybe I had to crank up the volume b/c the 1st sub was switched off?

-David