5. Can the E10K-TC's headphone, coaxial and line-out output work at the same time?

The E10K-TC supports 3.5mm single-ended headphone, coaxial and line-out output. 
(The coaxial can support up to 192k/24bit output.)

The E10K-TC's headphone, coaxial and line-out output can work at the same time.