Hi Bifwyne even the Magico S-5s are a hard load, just because they are a quite flat impedance, they are still 2ohms 50hz-80hz and then 3ohms 7khz-20khz.
But this isn't the only reason that them a heavy load.
It's the -phase angle at those impedances, which are -45 degrees at 50hz and -35 degrees in the mids/highs. (last graph on your link)
This will make the 2ohm load and 3ohm load look more like 1ohm and 2ohm to the amplifier, quite savage.
When you combine low impedance and high - phase angle as this, it's called EPDR (equivalent peak dissipation resistance) and the amp sees this as a much low resistive load.
Read about EPDR here, 5th page down under Lab Report. On the Wilson Alexia's It's PDF so you have to open it. I'll post more links on this EPDR if anyone's interested.
http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCIQFjAB&url=http%3A%2F%2Fwww.absolutesounds.com%2Fpdf%2Fmain%2Fpress%2FWA%2520Alexia%2520HFN%25200313-4web.pdf&ei=LFLAVO-6L8LVmgWqyICoBA&usg=AFQjCNEZq3-yhO0zaUOpAjBxXfWo_vYFLQ
Cheers George
But this isn't the only reason that them a heavy load.
It's the -phase angle at those impedances, which are -45 degrees at 50hz and -35 degrees in the mids/highs. (last graph on your link)
This will make the 2ohm load and 3ohm load look more like 1ohm and 2ohm to the amplifier, quite savage.
When you combine low impedance and high - phase angle as this, it's called EPDR (equivalent peak dissipation resistance) and the amp sees this as a much low resistive load.
Read about EPDR here, 5th page down under Lab Report. On the Wilson Alexia's It's PDF so you have to open it. I'll post more links on this EPDR if anyone's interested.
http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCIQFjAB&url=http%3A%2F%2Fwww.absolutesounds.com%2Fpdf%2Fmain%2Fpress%2FWA%2520Alexia%2520HFN%25200313-4web.pdf&ei=LFLAVO-6L8LVmgWqyICoBA&usg=AFQjCNEZq3-yhO0zaUOpAjBxXfWo_vYFLQ
Cheers George