"Does this method we are talking about have a bad effect on the full range sound?"
IMO, No if you can get it set up properly. Possible issues that may come up are; any overlap of the main speakers and subs as well as phase issues at the crossover point.
"Also, does adding a sub in the manner we are describing make the main amp work harder than if there were no subs at all?"
No. What I was talking about is in a true biamp set up (active crossover before the amps and sub's) I'd be removing the deep bass, below the crossover point, from the main amps. Simply put this would remove some of the demands on the amp since the bass requires much more power than the mids and highs do. My main speakers would also perform better as they would no longer be asked to do the deep bass.
The system would be able to play louder with less distortion. However in my case the quality of the mids and highs are negatively impacted by all of the active crossovers that I have tried so far. So I am running the SET amp and main speakers full range and using subs to augment the bass the main speakers can't do. After much "dialing in" the set up I am very happy.
IMO, No if you can get it set up properly. Possible issues that may come up are; any overlap of the main speakers and subs as well as phase issues at the crossover point.
"Also, does adding a sub in the manner we are describing make the main amp work harder than if there were no subs at all?"
No. What I was talking about is in a true biamp set up (active crossover before the amps and sub's) I'd be removing the deep bass, below the crossover point, from the main amps. Simply put this would remove some of the demands on the amp since the bass requires much more power than the mids and highs do. My main speakers would also perform better as they would no longer be asked to do the deep bass.
The system would be able to play louder with less distortion. However in my case the quality of the mids and highs are negatively impacted by all of the active crossovers that I have tried so far. So I am running the SET amp and main speakers full range and using subs to augment the bass the main speakers can't do. After much "dialing in" the set up I am very happy.