Will you agree that you would not be able to tell the difference between the $200 Pioneer and the 12K monoblocks?
Every amp doesn't sound radically different from others. But a 300B amp wouldn't sound anything like either of those. I don't put much stock in price differences, either. So many people here think that a price tag denotes a difference. Not always so.
The point I'm trying to make is that not all amps sound the same. If you pit two similar ones, it might be a tough call. If you pit two very different ones, detecting the difference will be easy.
That's why the challenge won't allow comparison of a 300B amp to either of those. The challenge itself admits that there is a difference.