Speaker sensitivity and impedance, explained
These two numbers decide how easily a receiver can drive a speaker — and whether the pairing you’re eyeing will play nicely or fight itself.
What does speaker sensitivity mean?
Sensitivity tells you how loud a speaker plays from a standard input, measured one meter away — an 88 dB speaker produces 88 dB from roughly one watt. The scale matters more than the number: every 3 dB of sensitivity halves the power needed for the same volume, so a 91 dB speaker needs half the amplifier of an 88 dB one to play equally loud. Higher sensitivity means an easier life for your receiver and more headroom before strain.
What is speaker impedance, and why does it matter?
Impedance (in ohms) is the electrical load the speaker presents, and lower means the amplifier must deliver more current. The “nominal” rating on the box is an average — many speakers rated 8Ω dip to 4Ω or below at certain frequencies, and those dips are what trip up modest receivers. A speaker with a low minimum impedance wants an amplifier built to supply current; pair it with one that can’t and you get distortion, a hot chassis, or shutdowns at volume.
How do you tell if a speaker is hard to drive?
Combine the two numbers into a simple difficulty score. Low sensitivity plus low impedance is the most demanding pairing and wants serious amplification; a sensitive speaker with a benign load is happy on almost any receiver. Spec sheets won’t say this out loud, which is why our compatibility checker weighs both numbers against the receiver you’ve chosen and flags the hard cases before you buy.