The SSR1 adds surround effect to any pair of stereo headphones--unfortunately, it doesn't do it well.
Featuring partially rubberized edges and an irregular shape, the small (roughly 5 by 2.5 by 0.5 inches), gray plastic unit looks and feels cheap. The device's main facing is distinguished only by green and red status LEDs along with relatively large Koss and SSR1 logos. If you grip the SSR1 the way its designers clearly intended, the tiny, side-mounted controls (volume and surround-sound level wheels, plus a surround-sound on/off switch) are easily accessible with your thumb. On the other hand, when the SSR1 is placed flat on a table as it would be when you're playing a video game, the controls are less easily adjusted.
On opposite ends of SSR1, you'll find a 1/8-inch headphone output and a 1/8-inch stereo audio source device input. The unit is thoughtfully supplied with both 8-foot and 1-foot cords; you can use either to connect the audio source device. Two AAAs supply up to 30 hours of battery life, according to Koss. You can still hear the audio when the surround-sound effect is switched off, but doing so deactivates the SSR1's volume control.
Although we've recently tested a couple of inexpensive but respectable headphone surround-sound simulators, the SSR1 didn't quite stack up. It made music (especially vocals) sound more reverberant and diffuse, but failed to place discrete sonic elements in distinguishable locations surrounding my head. What's more, the SSR1 added audible white noise to quiet passages. When we fired up Unreal Tournament 2004 on the PC, the results were similarly lukewarm. The best performance was with DVDs, such as Jurassic Park, where the SSR1 did create a noticeably deeper soundstage during the initial Tyrannosaurus rex attack scene. Ultimately, however, the SSR1's surround-sound simulation came off as halfhearted.
Turtle Beach's Audio Advantage Micro ($29.99) surround-sound simulator lacks a hardware volume control, but it plugs into a notebook PC's USB port and has a digital output and software-based configuration. It's limited to PC audio sources, but it delivers the surround goods with more palpable effect.