Tri-wired and verticly bi-amped for most of the time I owned them. And yes it made a big difference even at low volumes. I’d like to see the little efficient 7-9 watt amps hit 101db at 19 hz. Not saying I listen to music like that, but i’ve Measured them hitting it with no distortion or lack of body. My normal listening is about 75-80 db in a very large room with tall ceilings.