MAB
Major Contributor
They really do sound the same. I linked a classic tests where amps from Pioneer mid-fi to Levinson, Futterman, etc. were indistinguishable among believers and skeptics of amp-differences.I hear what you are saying, logically it makes sense. On the other hand, it's hard to believe there are so many companies, and even within one company there are so many amp products, and they will all sound the same? They dont advertise as just 'more features', but that the sound is superior
Actual Double Blind Studies
I just read yet another person trying to defend a position related to audio by referencing "double blind studies" generally. The idea always sounds great as a listening test. Truly see if people are able to notice differences between things. If we use a fairly controlled method, this information...
www.audiosciencereview.com
The inverse is true: tell people that there is a difference in two setups when there is not. After listening ask them which setup is better and they will hallucinate differences.
Audio Listening Test That Fooled the Hollywood Sapphire Group
Some of the most highly trained audiophiles in the industry were asked to do a blind “A-B” listening comparison test of two audio circuits. Were they able to hear a difference, or were they fooled?
www.audioholics.com
Recently linked in this thread is an AES paper that summarizes many studies. It should also comprehensively answer your question. The paper is AES and is $30, but money well spent for many people compared to the money some people throw at amps thinking there is a night and day difference.
Catalogue of blind tests
Do partially-sighted speaker faceoffs tally well with blind test results? If they can be shown to tally well then we we can trust many comparisons - anyone can do a face off (and many do...), while blind tests are too tricky for most to attempt. Example: Audio Musings by Sean Olive A blog...
www.audiosciencereview.com
In summary, we are not just saying this. It is actually demonstrated in studies over and over, since several decades ago. If this was medical, the claims that bad sound occurs from cheap amps would (hopefully) have been struck down ages ago. But then bad sound never harmed anybody.