Looking at the attached charts, an X symbolizes that the listener was able to pick the correct amp. In session 1, I was correct 50% of the time, Gudrun was correct 60% of the time. Afterwards, we mentioned what specific details we THOUGHT we heard differences in, as before we got the results we were somewhat confident, but there really were none. We agreed it was impossible to tell a difference.
In session 2, Dr. Jon was correct 50% of the time, and Gudrun was correct 80% of the time. Gudrun admitted afterwards that she just got lucky guessing on this test, as she legitimately could not hear any differences.
In session 3, Dr. Jon was correct 60% of the time and I was correct 80% of the time. I'll openly admit too, it was just guessing, nothing more.
Doing these tests, it becomes obvious VERY quickly that the two amps sounded identical. There were NO differences between them. This is not like auditioning speakers, where differences are abundant and clear - these amps sounded exactly the same. I realize that some "hi end" amps add their own sonic signature with a NON-flat FR response, but that wasn't the case with these two. If we had the time and patience to do more trials per session, say 20-40, I am positive all results would have been right around 50%. I believe Dr. Jon will agree to that - he will likely chime in on this thread.