Actually, there are speakers that sound like headphones and give a similar sound. Try the older (vintage) Polk SDA Series speakers from the 80s. They acoustically subtract inter-aural crosstalk to give you a headphone like sound. Carver, with their sonic holography did something similar electronically with some of their preamps during the same era. Some really liked the sound, others did not. On certain recordings it could sound very very good.
