Did they mentioned about signal purity? I would have thought it would be a cleaner process going from the amp's pre-out straight into the sub, but am dying to know why REL think high level is the way to go.
I don't know how well the different types of signals travel over cable to the sub. They are both 10m leads in my case, so not sure if that is a factor as well.
The final theory is I wonder if REL's point is related to crossover point - hoping a high level signal will be more cohesive. Because mine is so low, 40hz, I am not asking the sub to do a lot, and integration may be less of a problem and this may favour low level. I' ve searched the web high and low on the subject, to no avail.
May be a REL or EPOS god will look down from the heavens and bestow wisdom on the mortals.