Do amps degrade over time?

Most of my system is fairly new but I have a 15 year old Sunfire Cinema Grand amp. I had it serviced and recapped a few years ago when it started giving a buzzing sound (I realize capacitors need to be replaced after a while). I'm wondering if it's worth upgrading it. To be honest, I would probably replace it with something similar but newer. So my question is: Does the performance of a solid state amp degrade over time sonically? Would I get an improvement in sound quality with a newer amp? Or should I just keep using it until it really breaks down?