OSD Audio SVC405 Rotary volume control volume control

300W VC, A/B Switch, 20Hz - 20kHz, 42 dB OSD Audio’s SVC-405 is a flexible impedance-matching volume control that features a 2-way (A/B) switch. This switch gives you two connection options: 1) add two sources (i.e., one amp and one receiver) and a single speaker pair; or 2) use a single source (i.e., one amp) and connect two pairs of speakers, then use the A/B switch to choose between the zones.