If the 20.7 series is not bi-ampable and if your current 20.1's are bi-amped then it seems a little hard to compare. You can't compare bi-amped speakers with single amped speakers - on the other hand if your 20.1's are already bi-amped that's what you have to comare.
I bet no one will make such a comparison.
I bet no one will make such a comparison.