Lena is correct. That switch is there to keep the amplifier from overextending it'self. It speaks volumes about the amplifier (receiver) with such switches, none of it good. Too small power supplies, lack of sufficient output transistors and heatsinking are some of the cost cutting measures on these "units". An adequately designed power amp does not need such switches, and should take lower impedances in stride, ideally doubling it's power output for each halving of load impedance (up to a certain point!)

[This message has been edited by soundhound (edited May 05, 2003).]