Car amplifiers from US brands and US-based sellers

What to look for in a good car amplifier

• RMS vs peak power. Check for a continuous RMS rating tested at a stated voltage and impedance, since cheap units advertise a peak number that the amp can hit for maybe half a second before clipping.
• Heat sink mass. Pick it up: a quality amp has a thick, finned aluminum case that acts as the actual heat sink, while a knockoff has a thin shell bolted over a board that runs hot and shuts down on long drives.
• Input and speaker terminals. Look for solid screw-down binding posts that accept real 4 or 8 gauge wire, not the spring-loaded clips that back out with road vibration.
• Protection circuits. A legitimate amp lists thermal shutdown, short circuit, and DC offset protection on the spec sheet, since those circuits are the first thing cut to hit a bargain price around $70.