[wegs]

... I'm not so sure about that. I suspect you might have liked the way the speaker changed the sound, but you could have gotten the same effect (with greater control) with the headphones and digital preprocessing.

The headphones will give a more faithful reproduction of the original recording.

Making a nearly-perfect class D amp isn't hard (which is not to say a lot of people haven't messed it up; there are a lot of pretty bad amps out there).

The hard part is the speaker itself. The mechanicals of moving a lot of air accurately are hard. You need a physically large woofer which moves over a long distance. If you do that, your woofer and tweater won't be in the same place, so your phase response will be wonky. You don't want the air cavity acting as a spring overpowering your driver, so you need a large box. Etc. By the end of it, it's super-complex. Headphones are super-easy in comparison.