Performance that deteriorates slowly, in tubes or anything else, is difficult for a user to recognize. Think about your eyes. They seem to be OK until the optometrist says you need new glasses. One nice thing about ss amps is that, unless they emit a puff of blue smoke, they are probably OK. With tubes I found that I was constantly worrying about them, listening for problems, which detracted from the musical experience.
Listening for tube degradation
Hey, just wondering what specifically there is to listen for in regards to tube degradation. I don't have access to test equipment so I have to rely on my ear to determine if certain tubes are on their last legs. I've been able to notice a definite "scratching" or muddied sound whenever one or more of the tubes are in need of replacement. However, I find myself replacing ALL of the tubes since I can never pinpoint which exact tube or tubes needs replacing. Also, are there any visual cues to look for (ie.output tubes glowing brighter than others)? I have a 15W integrated tube amp that you can look at on my system page.