I think the comparison is far more drastic than that. I would compare $100 headphones (like your Sonys) to amplifier speaker set up of at least $2000. That depth of bass response and accuracy is quite an achievement for speakers.
I say this as someone with both Sony MDRV6 headphones and a home borderline audiophile stereo setup retailing for over $3k.
This is anecdotal and I mentioned this somewhere else in this thread, but I did a quick shootout between my Sony MDR7506 and a $80 Soundcore Motion+ bluetooth speaker and the Soundcore actually blew the 7506 away.
TBF I was powering the headphones with just my Pixel 3, but it's not a particularly hard to drive headphone.
There's been quite a bit of advancement recently with bluetooth speakers, and we'll probably see some more disruption in the affordable hi-fi space soon with what Purifi is doing with Class D amps.
... 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.
I say this as someone with both Sony MDRV6 headphones and a home borderline audiophile stereo setup retailing for over $3k.