So, I am composing a piece representing winter and I am right in the middle of the piece (the piece is in Rondo form and I'm at the C section).
I started off in E major, then after being in the subdominant for a while, I went back to E major. That plagal motion is very smooth indeed. Then I switched from major to minor. Then, through a scalar motive of a minor third, I went from E minor to where I am at now, C major.
C major and E major are chromatic mediant chords. I have done smooth modulations in multiple ways, but one way in which I haven't done smooth modulations is by using an omnibus progression. An omnibus progression basically boils down to this:
Bass moves down a half step at a time
Upper voice moves up a half step at a time
Inner voices stay constant or if they need to move, the motion is minimal
Since I am writing the piece for a trio of piano, violin, and flute, it should probably be either the flute or the violin that takes the upper voice of the omnibus progression. That way the pianist doesn't run into the problem of unreachable notes(Which, as a pianist myself, I know that a ninth interval is the maximum interval size I can play and that while I can double the root and play all 4 notes in a diminished seventh, making 5 notes in an octave total, it is quite uncomfortable).
Now, I know that the second to last chord, I want to be either a B7 or a D#°7, since both of those are dominant function chords that will smoothly resolve to E major. Since I am in C major at the moment, I want to know if I can start with C major or a closely related chord to C major and use the omnibus progression to modulate to E major. I know that some keys are reachable by an omnibus progression from a certain chord and others aren't(at least if you are taking about using the dominant or leading tone chord of the new key to confirm a modulation to the new key).
But can E major be reached by an omnibus progression from C major or a chord closely related to C major? Or is the major mediant, which has a chromatic mediant relationship to C major unreachable by this method?