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?
As you state capacitors partially electrolytic do degrade over time, a hum is normally the first sign that a cap is on the way out. Visually it may show signs of leakage or swelling.
I would look first at the power supply section, it’s likely a main power cap is at fault.

Other components can also degrade a little, like resistors, more so Power types, but it’s unlikely you’ll find many of those in a modern amp these day’s. Most solid state devices tend to last, unless shorted out or they over heating for any reason, if any blow it’s often due to a another faulty component down the line.
It seems your amp has two large 20,000uf electrolytic capacitors for the power supply, so I would say they need changing. It’s well worth having it serviced. Good luck.
If it sounds good, leave it be. If you have the upgrade bug, shop for something new.
Amps are pretty much just amp amp until it breaks.
Exception is tubed amps..
"If it sounds good, leave it be. If you have the upgrade bug, shop for something new."

Yes. I'll add if you like the "Sunfire sound" then keep it.
Also, since your amp is 15 years old, it was built in USA.
Entropy happens!
DON'T We All
"01-16-13: Lowrider57
Also, since your amp is 15 years old, it was built in USA."

Indeed. On the back it says "Made in Snohomish Washington".
Yes the sound degrades. Get all the capacitors replaced and it will sound as good as new maybe even better after new, better replacement capacitors are fully broken in.
Transistors also degrade over time but it usually takes longer than 15 years. By the time the unit is 30 years old one can expect a higher noise floor, not only from the transistors but also the resistors. Corrosion can also cause semiconductors to fail for no apparent reason. This is usually a problem associated more with ICs but it can certainly affect discrete devices also.

For now though, since you already have the power supply filter caps replaced, I would expect no worries for quite some time.
Second Thesoundhouse. Some of those older circuits are truly SOA. The right tech with the right upgrades will give anything current a serious run for it's money.
Thanks for the responses. My upgrade bug has been satisfied (and my wallet lightened) by recent purchases, so I think I'll be hanging on the amp for a while.