Hard to say since in some cases like the EP500 the amp controls have changed. In my case anything above about the 6:30-7:00 position causes my receiver to set it a -12db. Others with the newer amp controls have had to set it closer to the 12:00 position.
I’d start at 1/4 like Ken suggested and run your auto-call and if it get set close to 0 your good. If you have an SPL meter you could just match it to the rest of your speakers which is what I do since I find that receiver auto-setups have always been of 2-3dB when I use them on the sub.