Based on work I have done with the XDA-2 DAC, I would say that the output buffer of the ERC-3 is fully balanced. However, it is difficult to say for sure if it is fully balanced from the DAC chip and I/V stages.
https://emotiva.com/sites/default/files/styles/product_very_large/public/ERC3_TOP.png?itok=cjgxjTHQ
There are four op amps right next to the AD1955 DAC chip, so it could very well be fully balanced through the I/V and low pass filter stages. Emotiva likes to use OPA2134 op amps. These are somewhat laid back with a warm full sound, but definitely not as high-resolution as other op amps, such as the bipolar op amps (i.e. OPA1612 or AD797).