My subwoofer is a Kenwood KFC-W3010... some specs...
[TABLE="class: product_features_table, width: 720"]
<tbody>[TR="class: alt"]
[TD="class: feature_name, bgcolor: #F4F5F7"]Subwoofer Size[/TD]
[TD="bgcolor: #F4F5F7"]12"[/TD]
[/TR]
[TR]
[TD="class: feature_name"]Peak Power Handling[/TD]
[TD]1000 watts[/TD]
[/TR]
[TR="class: alt"]
[TD="class: feature_name, bgcolor: #F4F5F7"]RMS Power Handling[/TD]
[TD="bgcolor: #F4F5F7"]35 - 200 watts[/TD]
[/TR]
[TR]
[TD="class: feature_name"]Voice Coil(s)[/TD]
[TD]Single[/TD]
[/TR]
[TR="class: alt"]
[TD="class: feature_name, bgcolor: #F4F5F7"]Impedance (Per Voice Coil)[/TD]
[TD="bgcolor: #F4F5F7"]4 ohms[/TD]
[/TR]
[TR="class: alt"]
[TD="class: feature_name, bgcolor: #F4F5F7"]Frequency Response[/TD]
[TD="bgcolor: #F4F5F7"]25 - 800 Hz[/TD]
[/TR]
[TR]
[TD="class: feature_name, bgcolor: #EBF5FC"]Sensitivity[/TD]
[TD="bgcolor: #EBF5FC"]93 dB[/TD]
[/TR]
[TR="class: alt"]
[TD="class: feature_name, bgcolor: #F4F5F7"]Xmax (millimeters)[/TD]
[TD="bgcolor: #F4F5F7"]8 mm[/TD]
[/TR]
[TR]
[TD="class: feature_name"]Woofer Composition[/TD]
[TD]Pearl mica IMPP[/TD]
[/TR]
[TR="class: alt"]
[TD="class: feature_name, bgcolor: #F4F5F7"]Woofer Surround[/TD]
[TD="bgcolor: #F4F5F7"]Urethane[/TD]
[/TR]
</tbody>[/TABLE]
The rears (Pioneer TS-D691S) are also 4 ohms.