This is an auction for the VOSS PS-A254B, a 4-channel power amplifier made by Victor's professional audio brand, VOSS. This product has RCA input terminals and push-type speaker terminals, making it easy to connect to general equipment and also easy to use for surround sound. The rated output is 20W+20W at 8Ω, which may seem underpowered at first glance, but this is the standard for a professional amplifier's 20W. As a test, I connected the currently listed JBL8330 and directly connected an iPhone. Even with the volume at the 9 o'clock position, a sound pressure level of 90dB was achieved at the listening position. The product has normal output sound pressure for channels 1-4, and there is no scratchiness in the volume. It also supports BTL mode, but I haven't used it because it puts a load on the amplifier, and it's better not to use it. A copy of the instruction manual is included.