I've dabbled with both and find it hard to believe anyone thinks, price per performance-wise, that speaker could ever beat headphones. I've had some decent 5.1 setups and even decent 2.1's for my computer in the past and they are miles away when it comes to the headphones. Maybe I just don't have an acute ear for these things.
Well your mistake number 1 is comparing 5.1 or 2.1 systems with headphones. Stereo is what is for music. A stereo 2.0 setup will beat any 2.1 or 5.1 or 7.1 system in terms of sound quality when listening to music. Mistake number 2 is comparing computer speakers with headphones, which is silly. The best computer speakers on the market aren't a shadow next to 300$ bookshelfs. Honestly, I'm complete opposite, I find it hard to believe that anyone could like headphones more than speakers. As soon as we go past 500-600$ for a setup, speakers are superior, even when not ideally set up. I say, I doubt any headphone setup in the world available today, regardless of price could beat a 1500-2000$ speaker setup. Not to mention a 10000$ speaker setup, which is about the price of the most expensive headphone setup available new, Stax 009 and an amp for it.