1992 NAD 3020i hi-fi amplifier. Used most days. Still sounds great. Does that count? ;). How about a "Tesco Value" Microwave (yes that really was the brand), bought for £22 in 2006, still used many times a day?
you might want to take a look at the capacitors of the amplifier and potentially replace them. If they have degraded, replacing them would make it sound even better. Apart from such a degradation modern stereo amplifiers are likely not any better, so it's smart to keep it.