Check the listing for details. Vintage Optimus Model No: 31-2030 Ten Band Stereo Frequency Equalizer Tested. Color: Black, Condition: Used. Listed at 79.95 USD. Enhance your audio experience with this vintage Optimus Model No: 31-2030 Ten Band Stereo Frequency Equalizer. This analog and digital equalizer boasts a sleek black design, manufactured in Korea, Republic of in 1996. The equalizer features surround sound formats with an image enhancer, three audio outputs, and two audio inputs, making it a versatile addition to any home audio setup. With a power output of 110W, this equalizer is perfect for those who want to elevate their audio quality. The unit quantity is one, and it comes with a range of features including analog and digital capabilities, RCA and stereo L/R RCA audio inputs, and three outputs. This equalizer is a must-have for any audiophile looking to enhance their music listening experience.