A well made amp can last 20 years or more. For an amp, it's not a bad deal since (so far) the technology has not changed. It's still basically analog in, analog out, though digital amplifiers are starting to appear. The preamp is where the major changes take place. In the last 10 years we've seen DD5.1, DTS, component video, DVI, HDMI, HDCP and several lossless audio formats appear. New audio and video standards are already in the works so it isn't going to stop soon. Amplifier and speaker technologies are still basically the same as they were 50 years ago, though improvements in materials and design have made significant improvements in performance.