Thanks for the feeback again. I posted the same post on the Axiom Forum for 990 users, and the majority of feedback suggested adding 2.5' to 4' of delay to the actual distance to account for the digital delay of the EP500 sub. Here's a related question: Would it be possible to play a series of single frequency tones below 100Hz or so simultaneously through my mains and sub, and listen for the distance setting that sounds most synched? Kind of like performing relative tuning of strings on a guitar.