One of life's most embarrassing moments — you're mesmerizing your friends with your knowledge of musical lyrics, and one of them says, "Umm...that's not the way it goes."

Chances are you suffered this musical faux pas because you were listening to weak, ill-defined sound from a factory sound system and misunderstood a key word or a phrase.

The good news — there's no better way to dispel muddy sound than with an amplifier. An amp can help you get the most from your factory system — especially in a larger van or SUV, where it's really tough to achieve clean, powerful sound.

Speaker-level inputs let you connect an amplifier to your factory stereo system.

The value of speaker-level inputs

Factory radios do not have dedicated outputs for amplifiers (preamp outputs). So you'll want an amplifier with speaker-level (often called high-level) inputs; these inputs enable you to tap into the factory speaker wires for a signal flow.

They're called high-level inputs because the voltage level is significantly higher than with a standard preamp output connection. These inputs convert the high voltage to one the amplifier can handle. Once connected, you'll hear clean, well-defined sound (including the lyrics to your favorite song).

Speaker-level inputs are a standard of many two- and four-channel, and mono subwoofer amplifiers.