  We present new ALMA observations of CO $J$=2$-$1 line emission from the DQ
Tau circumbinary disk. These data are used to tomographically reconstruct the
Keplerian disk velocity field in a forward-modeling inference framework, and
thereby provide a dynamical constraint on the mass of the DQ Tau binary of
$M_\ast = 1.27_{-0.27}^{+0.46} \,M_\odot$. Those results are compared with an
updated and improved orbital solution for this double-lined system based on
long-term monitoring of its stellar radial velocities. Both of these
independent dynamical constraints on the binary mass are in excellent
agreement: taken together, they demonstrate that the DQ Tau system mass is
$1.21\pm0.26\,M_\odot$ and that the disk and binary orbital planes are aligned
within $3^\circ$ (at 3$\sigma$ confidence). The predictions of various
theoretical models for pre-main sequence stellar evolution are also consistent
with these masses, although more detailed comparisons are difficult due to
lingering uncertainties in the photospheric properties of the individual
components. DQ Tau is the third nearly equal-mass double-lined spectroscopic
binary with a circumbinary disk that has been dynamically "weighed" with these
two independent techniques: all show consistent results, validating the overall
accuracy of the disk-based approach and demonstrating that it can be robustly
applied to large samples of young, single stars as ALMA ramps up to operations
at full capacity.
