Bear with me after my butchered title.
I was thinking about the Richard Clark $10,000 amplifier challenge, which provides a $10,000 reward to anyone who can discern between any 2 amps, after equalisation has been applied (to either amp, of the challenger's choice) to match them.
This means that a Class D amp can be compared to a tube amp, as long as equalisation is applied to either amp (of the challenger's chosing) to make it sound like the other. No one has yet won. One conclusion that seems fair to reach then is that anyone can grab a cheap class D and an equaliser and with enough time make it sound like a tube amp, or the best mcintosh.
To take this a step further- why would this not work with other gear too? I'm a vinyl guy and obviously you can't equalise a cartridge to make it track better or minimise IGD, or even extract details tight from the groove , but I can't see why you couldn't take an at95e to equalise it to sound like a grado gold? It would certainly be inferior, but it would have that grado sweetness.
I suspect that a lot of high end amps sound the way that they do purely because the makers deliberately "equalise" them internally to sound the way it does. What's wrong with external equalisation if a high-end amp only sounds the way it does due to internal equalisation?
Quick edit: A common misconception I see elsewhere about this challenge is that it requires equalisation to be put on the better amp to dull it down to the standards of the lesser amp. That isn't the case. The equalisation can be applied to the lesser amp to bring it to the same response of the better amp. The challenger gets to pick which amp sees the EQ