Tube equipment has a very distinctive sound due to distortion.
Tubes devices are also more linear than solid state devices without the use of feedback, Which also could have something to do with the way they sound.
Amir and Blind Testing
Let me start by saying I like watching Amir from ASR, so please let’s not get harsh or the thread will be deleted. Many times, Amir has noted that when we’re inserting a new component in our system, our brains go into (to paraphrase) “analytical mode” and we start hearing imaginary improvements. He has reiterated this many times, saying that when he switched to an expensive cable he heard improvements, but when he switched back to the cheap one, he also heard improvements because the brain switches from “music enjoyment mode” to “analytical mode.” Following this logic, which I agree with, wouldn’t blind testing, or any A/B testing be compromised because our brains are always in analytical mode and therefore feeding us inaccurate data? Seems to me you need to relax for a few hours at least and listen to a variety of music before your brain can accurately assess whether something is an actual improvement. Perhaps A/B testing is a strawman argument, because the human brain is not a spectrum analyzer. We are too affected by our biases to come up with any valid data. Maybe.