I am trying to use my quantum 2626 thunderbolt along with my Eros e8 xt studio monitor es ‘s along with an Alesia sr 16 drum machine as a metronome for rehearsal purposes... however I am unable to achieve playback through both monitors.... it seems as if neither of my main outputs are working... and only one of the pre amp outputs are which is why for some reason I am able to get one speaker to work ... help please