"My old amp just blew up!" (Be glad!)
So, you have had a nice amplifier for years. One day, out of the blue, it makes a rude noise and stops working. Be happy. You don't know what you have been missing for the last ten or twenty years. Time marches on and the audio industry gets better with each passing year. Most good audio manufacturers redesign and improve their amplifiers (and other components) every five years or even more often. Each time they get a bit better sound - more smoothness, more dimensionality, more clarity, better harmonics. One generation to the next alone is usually better enough to hear the difference pretty quickly. Four or five generations over twenty years is a big difference. Better circuit design, improved, better sounding parts, capacitors, resistors and surface-mount miniaturized parts all make for better sound.
We recently traded-in an amplifier that was two generations in the past and connected it to a known speaker system in place of a current model amplfier of the same well-regarded manufacturer. Within a short listening we concluded that the old amplifier's sound quality would be unsaleable against the industries current offerings. So...when your amplfier fails, don't be sad, be glad! Better yet, it you are a serious music listener with an old amplfier, improve you system with a new amplfier. ☺