9 o'clock on the 500 and 600 is not "barely on". The dial orientation on the EP's are different than the other subs. Most of us run ours around 6-7 o'clock, allowing the reciever to be in the -6dB neighborhood. I would not have the receiver set to low, just my opinion.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85