A well made solid state amp should last at least 15 to 20 years. A 4 or 5 year old solid state amp should last you at least another 10 years. I recently had two capacitors replaced on my Acoustic Research Amp, which I bought new in 1969(!!). Actually, the amp developed audible problems late last year, but I didn't get around to taking it in until last month. (Perhaps it lasted such a long time because I have been playing more my newer equipment for the past few decades.)