You're thinking too deeply about it.
This is audiophoolery-buy one and try it. There are plenty of happy REL users. The one that aren't simply didn't hear what they were expecting, and went with another brand.
Does a REL subwoofer make the speakers' job easier?
Gentlemen,
Let’s assume we are following REL’s recommendation by connecting the sub to the amp instead of the preamp through the high-level connection. Then which one of these two would be true?
1. The sub would make the speakers’ job easier by not sending the low bass signal (i.e., below the crossover point) to them.
2. The signal sent to the speakers would still include the low bass even when the sub is used. Therefore the speakers would still receive the full range signal.
If (1) is true, how is it accomplished electrically? I am asking this as someone who has little knowledge about how the signal flow between amp and speakers works.
Thanks in advance!