Warm TipsSP-220S version has a volume control knob, can adjust the audio source volume; Features2-IN-4-OUT Audio selector, the input can be connected to 2 amplifiers, and the output has 4 interfaces, which can be connected to speakers.The panel has Push-Button input and output switching buttons, manual switching, stable sound without interference; no need to plug in, easy to use and save energy.There is a non-slip pad at the bottom to protect your desktop; using audio equipment with a switch can avoid the wear and tear of the interface caused by plugging and plugging, and prolong the service life of the audio equipment.ParametersSP-24B VersionAudio input: Stereo RCA*2Audio output: Stereo RCA*4Dimensions(W*D*H): 160*120*40mm/6.30*4.72*1.57inNet weight: 270g/0.60lbPackage weight: 500g/1.10lbSP-24 VersionAudio input: Speaker jacks*2Audio output: Speaker jacks *4Dimensions(W*D*H): 160*120*40mm/6.30*4.72*1.57inNet weight: 270g/0.60lbPackage weight: 500g/1.10lbSP-220S VersionAudio input: Stereo RCA*2Audio output: Stereo RCA*4Dimensions(W*D*H): 143*160*62mmPacking List1*Speaker Selector Box