I’m kind of late in the convo here, but ...
the original “experiment” by Mr Walker was more of a sham, not a true experiment that controls for all/most variables as we do it in the real world.
He found 2 different amps, ONE SS and ONE tube, but ran them through the SAME speakers. The speakers are the last units in the sonic chain to impart sonic influence on the final sound.
1. Change the speakers and I will not get the same sound from the 2 different amps most of the time. Do this test with 100 different speakers, and IMO over 50 of the tests will reveal different sounds even with the same SS/tube amps.
Synergy, remember?
Because different speakers have different properties and sonic signatures. e.g., # of cones and drivers, size and type of drivers, 4 Ohm vs 8 ohm , vs 16 ohm, etc