Having just purchased a pair of Sennheiser HD515's (open back), it has got me wondering; How much would I have to spend on speakers before I could achieve a similar amount of detail afforded by the senny's?
Even though my second system is quite detailed (Gainclone/DIY active pre/Modified Toshiba SD100E DVD/Modified Tannoy mercury M1's), it comes nowhere near my 515's using my DIY headphone amp (Class A single MOSFET) and same source.
I am now able to hear things in recordings which I hadn't previously heared. Maybe I could put it down to the ambient noise when listening to the speaker set up, but as I do most of my serious listening late at night, I'm not sure that it makes too much difference.
I know that my source, Pre and Power amp are all very capable, and that my speakers definately let the side down. But I guess you have sacrifice a fair amount of detail for freedom and scale when using speakers over headphones.