Amazon.com: Gikfun 4Ohm 40mm Diameter 3W Full Range Audio Speaker Stereo Woofer Loudspeaker for Arduino (Pack of 2pcs) EK1794 : Electronics
Amazon.com: 180W(Peak Power) Wireless Bluetooth Stereo Amplifier, Sunbuck Dual Channel Sound Power Audio Receiver w/USB, SD Card, FM Radio for Home Theater Entertainment Speakers with Remote Control (AS-25BU) : Electronics
Amazon.com: 4 Ohm Speaker
Amazon.com: BOSS Audio Systems R1100MK Car Amplifier and 8 Gauge Wiring Kit - 1100 Watts Max Power, 2-4 Ohm Stable, Class A/B, Monoblock, Mosfet Power Supply, Remote Subwoofer Control : Everything Else