A terrific choice for a remarkably affordable system upgrade or building block, the AudioSource Amp 200 high-current stereo power amplifier offers 80 watts RMS per channel x 2 or, in bridged mono mode, up to 250 watts x 1 (into 8-ohm speakers in both cases). Now you can scale your listening to match your budget: use either 1 amplifier or 2 for stereo sound or 5 or more in concert for full-blown home-theater excitement--perfect for your DVDs, multichannel DTV broadcasts, or high-resolution audio formats like DVD-Audio and SACD.

Keep in mind that this is an amplifier only, with no volume control or onboard surround processing (though it does offer independent adjustable output controls for each channel). It's designed for use with a stereo preamplifier or a surround receiver offering preamplifier outputs.

Making the move from 5.1- to 6.1- or 7.1-channel surround sound? If your receiver has preamp outputs for all channels, there's no need to replace your 5.1 surround receiver. Just feed the additional center or surround signals to a strategically positioned Amp 200.

Connections consist of a choice of RCA (line-level) or clip-type (speaker-level) inputs and banana-plug-friendly binding-post speaker terminals for outputs. There's also set of stereo (left/right) RCA passthrough jacks for use in a daisy-chain setup.

The amp works with 12-volt power-on/-off circuitry and also features a signal-sensing circuit for automatic power-on/-off, making it as ideal for custom installers as for end users. Its A and B speaker outputs let you power speakers in your main room, a second room, or both rooms simultaneously. The amplifier's toroidal power supply keeps distortion extremely low (less than 0.04 percent).