Haven't thought much about dacs at this moment. But i'm only going to focus on dacs after improving my amp section. You're right about the lcd-x though, there is no point in adding more headphones to your collection without having proper amps to drive your current phones to their maximum potential.
That's all fine and dandy but if your source is not good, the amplified version will be terrible. The window to your music is the source (which may or may not include the DAC). If DAC is of secondary importance, that's ok but make sure your music files are very good.