KENWOOD KA-V7700 Original retail price: ¥89,800 This is the main unit only, but it works without any problems. I think it can still be used. There are no noticeable scratches or stains on the exterior, but it is a used item, so please consider this before purchasing. [Excerpt from product description] An AV amplifier that combines a full-fledged high-quality amplifier with AV surround functions such as Dolby Pro Logic and DSP. Equipped with a DSP logic circuit that adds steering logic (directional emphasis circuit) to the DSP mode. By adding initial reflections and reverberation using DSP to the signal output from the directional emphasis circuit, a powerful sense of realism is achieved. Equipped with a digital processing Dolby Pro Logic surround decoder using a newly developed DSP LSI. The steering logic (directional emphasis circuit), which is important for Pro Logic, as well as the Dolby B circuit and auto input balance are processed with digital signals. This eliminates the problems that occurred when the Pro Logic stage was configured with analog components, such as the linearity of the VCA (voltage control amplifier), the accuracy of analog parts, and the complexity of the circuit, thereby improving sound quality. Equipped with a DSP presence circuit that controls initial reflections and reverberation through digital signal processing, creating a sound field space by combining it with the main signal. The structure converts analog signals to digital signals with a 64fs 4th-order noise shaping 1-bit A/D converter, and uses a dedicated DSP (digital signal processor) for arithmetic processing, allowing you to select from six types of sound field patterns. Equipped with a channel mode that distributes presence signals depending on the number of speakers and the setting. By switching the channel mode, you can enjoy DSP logic with 3ch (front 2ch + center) or 4ch (front 2ch + rear 2ch). There is also a position where you can enjoy DSP presence with only the front 2ch.