Aside from "in the head" imaging with headphones, I believe that ACCURACY is on the side of headphones. With GOOD, accurate (neutral tonal balance) headphones, you hear WHAT'S ON THE RECORDING, not a dilluted version of it.
It is literally impossible to listen to JUST speakers, for speakers ALWAYS interact with room acoustics, and sound different not just in every room, but in every position WITHIN that room! Headphones, on the other hand, have a DISTINCT advantage, especially for critical MONITORING, as the room acoustics can be COMPLETELY bypassed! What you hear is WHAT'S ON THE RECORDING (plus the colorations introduced by the headphones themselves), rather than what's on the recording, room acoustics (including standing waves/echoes/additional reverb/phase cancellation between drivers, and various RANDOM boosts and cancellations present in EVERY room, with EVERY speaker). Headphones also have another IMMENSE advantage over speakers...since it isn't necessary to generate room filling volumes at low frequencies, the entire audible spectrum can be reproduced by a single driver. No crossovers, with all their phase anomolies, and no multiple drivers, which will NEVER match perfectly, and will always intercourse the waveforms they reproduce in both time and frequency domains!
I admit that there's a certain "rightness" to speakers, largely due to the fact that in real life we don't just LISTEN to live music, we also FEEL it. Properly reproduced bass moves the room, and our bodies, not just the air. I believe that this is much of what people who prefer speakers are addicted to. But for me, when I really want to get INSIDE a recording, and experience what the musicians played, and exactly how they played it. it's no contest...headphones are FAR better to these ears!
