An amplifier is the engine of your audio system. Speakers need clean, sufficient power to perform at their best — and factory head units provide almost none. Choosing the right amplifier means matching wattage, impedance, class, and channel count to your specific build. Here's how to do it.
Amplifier Classes: What A, B, A/B, and D Mean
The "class" of an amplifier refers to how its output transistors are biased — which directly affects efficiency, heat, and sound character:
- Class A: Highest sound quality, extremely low distortion — but very inefficient and runs very hot. Rare in car audio.
- Class A/B: The most common type for speakers. Good sound quality with manageable heat. Ideal for front-stage channels.
- Class D: Very efficient and compact. Ideal for subwoofer amplifiers where power density matters more than subtle harmonic character.
- Class H: A hybrid approach that varies supply voltage dynamically. Very efficient, excellent for multi-channel amplifiers.
How Much Power Do You Actually Need?
This is the most misunderstood aspect of car audio amplification. Speakers are rated by RMS power — the continuous power they can handle indefinitely. Your amplifier should match or slightly exceed the speaker's RMS rating when measured at the speaker's impedance. More power doesn't necessarily mean louder — it means more headroom, less distortion, and better dynamics at all volume levels.
For a typical full system: a 4-channel amp (75–150W RMS per channel) for front speakers plus a mono amp (500–1000W RMS) for a subwoofer covers most builds comfortably. Premium speakers like the Audison Thesis TH quattro are designed to extract every last bit of that power without compromise.
Impedance Matching
Every speaker has an impedance — typically 2, 4, or 8 ohms. Amplifier power output changes with impedance: a 4-ohm load produces more power than an 8-ohm load from the same amplifier. Running speakers below the amplifier's rated minimum impedance causes overheating and failure. Our technicians calculate every impedance scenario before recommending an amp.
Electrical System Considerations
High-powered amplifiers draw significant current from your vehicle's electrical system. Anything above 500W total system power typically requires a big three upgrade (chassis grounds and alternator wire), a quality AGM battery like the Optima YellowTop, and properly sized power and ground wiring. The installation experts at Audio Matrix in Torrance, California (Southbay) handle the full electrical assessment as part of every amp installation.