603 S3

Headroom Notes

90 dB at 2.83 Vrms / 1 m on an 8-ohm nominal. Note that B&W quotes distortion conditions alongside — «<1% 100Hz - 22kHz» at 90 dB, 1 m on axis — which is rarer than the sensitivity figure itself and makes the number checkable in a way most of this batch is not.

Amplification Warning

The same 3.0 Ω minimum as the 607 S3 but 6 dB more sensitive, which changes the problem entirely: the 603 needs current rather than voltage. Two 165 mm paper bass cones in parallel are what pulls the impedance down. The upper recommendation of 200 W is not an invitation to use 200 W — it is B&W saying the speaker will survive an amplifier large enough not to clip into 3 ohms.