  We respond to a recent manuscript by Tsang [arXiv:1306.2699], on whether the
measurement presented in Safavi-Naeini et al. [Phys. Rev. Lett. 108, 033602
(2012)] can be explained "without reference to quantum mechanics". We show that
the fully classical analysis provided by Tsang, and previously by Safavi-Naeini
et al. [New J. Phys. 15, 035007 (2013)], has been ruled out by our published
data. In addition, we discuss the role of the mathematical formulation used on
the interpretation of the asymmetry effect, as has previously been considered
by Khalili et al. [Phys. Rev. A 86, 033840 (2012)].
