Great Question !!! My speakers have Sensitivity 90dB spl; Nominal Impedance 8 Ohm; Minimum 3.5 Ohm. The bass is on the light side (I use a REL sub) and very very slightly slower compared with the rest of the speaker. Is this reflected in the 3.5 minimum Ohms?? I've read an amplifier with a lower output impedence the better to drive the bass better. Is this true? Comments??