The proposition in this post contains too many variables to be worth discussing.
1. The choice of amplifiers is based solely on retail cost.
2. It cannot be assumed that cost is the only or even a main determinant of sound quality.
3. The conclusion allows nothing for listeners' taste in sound, although it is noted that a nearly all listeners came to the same conclusion.
4. The fact they did suggests that the choice of amplifiers was not optimal.
5. We are not told if the power amplifiers used have the same output rating. If they do not, this could affect how the loudspeakers are driven. A $1000 amp is very likely to output less power than a $3000 amp from the same manufacturer as this is the way a range of products is built up. How sensitive were the speakers used? If they were underdriven this will certainly alone explain the finding.
Some 30+ years ago I and a friend conducted an experiment with amplifiers using Audio Research and Krell products. We created a number of systems where the pre-amp was solid state and the power amp valve driven and vice-versa. We universally found we liked the rigs with valve pre-amps a lot better. Since that time my two systems have always been run that way.
Similarly, until I heard the van den Hul 'The Grail SB' I had always preferred the sound of valve phono amps, a series of Audio Research.
Looking for a big upgrade I found The Grail a lot better than the AR Reference and the other high end pieces I tried in my system. Go figure!
