Have you ever considered implementing an audiophile-quality bass boost feature for the DA11, say, for frequencies below 100Hz?
A boost would serve to ameliorate the tendency of the ear to get less volume from bass frequencies when the overall volume level is low. It would also serve to counter the recording practices of early pop/rock genres where the bass was mastered at a lower level than the midrange/treble. It can allow one to enjoy balanced hifi sounds at low levels at the office or elsewhere.
Rather than utilize a switch for such a boost, you might consider using a potentiometer. At the "0" setting, the boost would be completely off - as it should be for those recordings that don't require it. At higher settings the user can add as much bass as needed/desired.
