the vast majority of external headphone dacs are 2.0 stereo only. the only ones i'm aware of which are not would be the dss/dss2, mixamp, e1/x7/g5/recon and the ones which come inside gaming headsets.
none of which i would call "great" solutions as they all have their pro/con and problems/ issues to deal with be it rediculously high cost, build quality, sound quality or feature set..