Originally Posted by cetoole
Besides people with 'stats, 'trets, or piezos? Ortho heads take a pretty good amount of drive.
The electrostatics/piezo's do need more than 20v swing, but I think its safe to assume that since they will need a dedicated amp they can be considered separately. They still get by with less then 60dB of range.
orthodynamics dont take much more voltage than "cone and coil" dynamics. You may wind up shooting yourself in the foot with output impedances... but we are just talking about voltage swing
even if you consider the effects of highish output impedance on a low-impedance headphone you will probably still find you dont need 60db of control range to cover most dynamic (non-K1000) headphones.
1v (RMS) will make virtually any dynamic headphone play at stupid volume levels (including orthodynamics). The fact that the amp can swing 20v is barging rights and overhead. Is it worth adding more active parts to get a few dB of extra voltage headroom? I certainly agree there is a point below which your "headroom" is Inadequate, but once you pass that point... When you view active parts as distortion generators as well as voltage/current manipulators more is not necessarily better.
The fact that the amp has unity gain (or is an attenuator) does not detract from its ability to pass large signals. There are buffers designed to pass at least 20v. The nelson-pass/first watt F4 comes to mind.