Thanks for your advice!
Here is the thing that does not make since to me. It seems like if you set EACH subwoofer to 75dB with the sub trim level from the receiver set to 0dB, wouldn't you get more power or the maximum power from both subs?
I mean, why set BOTH subs to 75dB when you can get more maximum power coming out of BOTH subs. If each sub is putting out 75dB, and you set the other sub at 75dB, you would get the DOUBLE power from both subs.