I've got a pair of SDA IIs, an old Yamaha receiver, and a Hafler 9270 amplifier. When I connect the speakers straight to the receiver, the volume works, but I get a lot of distortion. When I connect the speakers to the amplifier, then to the receiver, the volume knob on the receiver doesn't work and everything plays at top volume.
I've tried an iPhone (using the 3.5 and the direct line out) and turntable as the music source with the same result.
Any ideas on what the issue could be and how to fix it?