They are all subject to measurement, but what many have found out is that the measurements do not give a complete picture of what something sounds like. It looks as if a different basis for the measurements still needs to be discovered as far as our goals are concerned. Many of the basics still hold true, but as far as certain distortion levels, RMS watts and perhaps even sine wave readings, they do not seem to hold as linear a relationship with audible performance as they were once thought to. Advancement in this area will most likely involve furthering our knowledge of the human senses and the brain. Until then let your ears be the judge as these tests will only tell you what you can already hear and comprehend.
Tube v. Solid State / Analog v. Digital
WHAT'S THE DEAL? I'M NOT AN ENGINEER OR AN AUDIOPHILE. I HAVE HAD KNOWLEDGEABLE PEOPLE SAY THE GOAL IS NO DISTORTION AND THAT CAN BEST BE ACHIEVED IN A DIGITAL/SOLID STATE/CD REALM. OTHER KNOWLEDGEABLE PEOPLE SAY THAT'S NOT TRUE. TUBES/ANALOG/VINYL IS IT. ALL I KNOW IS THAT DIGITAL/SOLID STATE/ CD IS SUBJECT TO MEASUREMENT AND ANALOG/TUBE/VINYL IS BASICALLY NOT. TO ME THE ULTIMATE OXYMORON IS A CD PLAYER WITH A TUBE STAGE IN IT. WHAT'S THE DEAL HERE?