Some have said that DBTs between relatively inexpensive ($250) amps and relatively expensive (>$3000) amps have proven that there are no audible diferences. Might I ask whether the people who participated in those tests were:
a) having good auditory capacity
b) aware of sounds enough to tell the difference

Enough people have listenened to magnaplanars and said that if I was all that interested in music reproduction - should really get the bose acoustimass type speakers. !!
If such people were participating in DBTs - well - all would come to naught. The Audio industry suffers (IMNHSO) because people (at large) are not all that attuned to sounds. Many are well attuned to visual/TV. They (IMNHSO) may pay some attention to sharp transients but they are satisfied with a wide range of quality of transients (ringing of swords, arrows hitting targets etc). Who even knows what a real sword fight should sound like ? Who uses bows and arrows enough to know what they sound like ?

I recently heard ROTEL 1080, Musical Fidelity HT100, Myryad MA240 swapped in my system - not by DBT...they are all comparably priced amps (all in the $1000 range) and the differences were not small. Music was mostly Jazz - Chesky Discs.

So although a "proper" DBT may be the answer finally - question is - has a "proper" DBT ever been done on Amps ? What kind of participants/music/sounds would be chosen ? Dont get me wrong - I am not really against DBTs but if the perfect DBT is not done yet - why accept it's/their imperfect conclusions ?