OSD Audio's SVC300 is an impedance-matching volume control that lets you adjust the volume of a pair of speakers independently of other speakers within a whole house audio system. Ideal for areas such dining or conference rooms where you may want softer volumes or for saunas or garages where you may want higher volumes, the SVC300 maintains the full hi-fi audio frequency response with no low frequency roll-off. Equipped with the same features of volume controls that cost twice as much, the SVC300 is rated at 300 Watts peak and includes adjustable jumpers to add up to eight pairs of 8-ohm speakers simultaneously. The impedance-matching feature helps stabilize the ohm load going back to the amp or receiver to avoid overheating and damaging expensive equipment. A complete volume control kit that fits into a standard single-gang box, the SVC300 also includes the junction box, screws and assorted color trim plates (white, ivory and almond) so you can choose the color that best matches the room. This versatile whole house volume control is compatible with almost any dedicated audio zone or whole house system, and the 12-step rotary knob adjusts the volume from inaudible to loud and everything in between.

Speakers are specified by impedance, which is a measurement of resistance to alternating current, and a common value for speakers is 8 ohms. When you're connecting multiple speakers to a receiver or amplifier, you need to stay above the amp's minimum load requirements because going below the impedance rating can overheat or even damage expensive equipment. The SVC300 allows you to match the impedance with the number of speakers being controlled with the capabilities of your amp. A basic multi-room system will typically have an amplifier/receiver, a speaker selector, four to eight pairs of speakers, and volume controls. Impedance-matching volume controls feature three settings depending on how many speakers you are connecting. For one to two pairs of 8-ohm speakers, the setting is 1/2x; for three or four pairs of 8 ohm speakers, the setting is 4X. Keep in mind that volume controls do not add gain (volume) to your speakers but simply attenuate the volume up or down. During setup, you'll set the source volume to its optimum level, then the volume control turns the sound down to inaudible levels.