I have that stack and two Topping a90 amps but I use the a30/d30pro daily since I tested them side by side for days and didn't notice on amp sounding any better even volume matching on the same setup.
The optical sounds best with a completely silent noise floor. I used the Hifiman he6se for comparing and didn't notice a difference. Having full power from all connections is the best, no more cable shopping or running out of volume equalizing the 600ohm Beyerdynamics.
Filter 2 and optical cable, as good as it gets.