My friend was using a Pioneer receiver at the time. Which one, I don't know. But the change (in sound quality) running each NAD 2200 bridged mono was very apparent. On the other hand, the power level was stupendous. The fact that we did not break the S.L. speakers was also a miracle. The 3 story house on 2 acres+ allowed us to operate the equipment as loud as we wanted, we'd just open the windows, crank the volume up & go outside to the barn. Eventually the barn was where we moved the system to: to avoid parental interference.i kinda remember s.l. speakers from the bygone days, but i really didn't put it all together until later that these are a reincarnation of vintage speakers from the 1960/70/80's.. i was really shocked at the sound quality...