I am not one who believes blind tests are the answer. What I do believe is that such tests are more than adequate to prove there are no night and day kind of differences between lots of well made pre-amps and power amps.
Yes, I agree but I want to qualify this & maybe by the end of reading this you will realise that I don't really agree
"night & day" is a loaded term often used to demean audiophiles. To the man in the street a "night & day" difference is the difference between a crystal radio & a modern radio. But when people get involved in a hobby small differences become amplified in rhetoric - it's the same with any hobby.
But there is a deeper aspect to this that I wanted to mention. I believe the phrase "night & day" often refers to the effect the music now has on us - the connection we now have with the recording - in essence it signifies that what we are listening to has become more realistic.
Now, auditory realism is far more complex then a simple change in frequency/ amplitude/ timing. Auditory realism is about how we perceive the audio spectrum of the real world & make sense of it. In other words how the brain processes the continuous stream of aural frequencies, amplitude & timing signals coming from both ears through the auditory cortex. In the same way as our visual system process the visual signals coming from both eyes & creates a visual scene in which are placed visual objects, our auditory system does the same. This is an active area of research called Auditory Scene Analysis (ASA) which is working towards establishing how the brain analyses the signals to produce a stable auditory scene with auditory objects.
ASA is not simple, as you might have guessed. How we establish an auditory scene & auditory objects in it is done by the brain analysing the relationships between elements in the continual signal stream & identifying relationships between certain parts of the signal stream which it groups together as coming from the one object & so on to form all the auditory objects that we create in what we hear & together this forms the auditory scene.
This is a continually shifting/modulating signal stream coming from the ears so there is continual analysis happening in real time. It correlates different parts of the signal across different time spans in the audio stream - in other words, it's not an instant decision it takes time to create an auditory object & scene & it continually adjusts this based on the new information arriving in the signal. This requires processing energy & also is stressful. Stressful in the sense that we never have enough information in the signal stream to be 100% sure of the auditory objects so all sorts of extra help is brought to bear on this ill-defined problem. We use visual cues - so for instance we look at a person's lips when they are talking as an aid to understanding what they are saying (particularly when there is a noisy background). In fact the whole study of this arose from what is called the "cocktail party effect" - the ability to follow a conversation among many others in a noisy party. We use our knowledge of the world - our past experience of how audio behaves in the world, etc. We use all sorts of extra information to fill in any void in the information that can be ascertained from the auditory signal. And there are always voids in the information - it is always an ill-defined problem - so we are always making a best guesstimate of the most likely solution & coming up with the most plausible scene.
ASA, is a research area still working on all of this & although some progress has been made since 1990 when Bregman published the theory/model, there is still a lot to be worked out about how our auditory perception works.
So here's where I get back to the idea about "subtle" changes Vs "night & day" changes. I think if you judge the sound using how realistic it is i.e relaxed listening to the full playback, you may well decide that it sounds much more realistic than what you heard before. This might even take a number of listens to different music over time to be sure about this because it's not a directly sensed immediate difference - it's more a realisation that you are picking up more auditory clues in the performance - maybe you can hear the interplay of the performers better or the acoustic space better? This assumes that the recordings have captured these aspects. This realism is the result of a steady auditory scene with easy to follow auditory objects within it. If something disturbs this rendition of the auditory scene i.e. one of the known ASA rules (or some of the unknown ones) is contravened in some way, we get a temporary break in the auditory scene & an immediate new rebuilding of the auditory scene. This is a subconscious event - we don't hear anything collapse - our perception adjusts to it subconsciously. But if this happens too much (& I don't know what too much is) when listening, I believe it gives rise to fatigue.
Now ask someone who has experienced a system that is more realistic or a system that is fatiguing to do a blind test to identify the playback he finds most realistic & I bet he will not be able to do it. I know the proponents of blind testing will say that he can listen for as long as he wants in a blind test - there is no need to do quick A/B switching & I would imagine this could be done but I imagine it's a very difficult test to pass successfully
My point is that "night & day" as judged from long term listening can change into "subtle" in blind testing if there are actually freq, amplitude or timing differences that can be identified in quick A/B switching. If there are no readily identifiable instant A/B differences then the task gets very much harder. Are there some people who could identify this - maybe a few but they need training in how to listen & what to listen for & probably a lot of experience in doing blind tests?
