Rock, Alan's excellent responses that you use the speaker level connections are the most practical with the equipment that you have. As he points out, the 386 has no balanced output, so that isn't an option. The two low level outputs can't be safely combined with a "Y" connector to feed the single EP500 low level input without creating a feedback of voltage into the 356.
There should be no level problem if you set the volume control on the EP500 at an appropriate setting. The bass control on the 356 should not be used.
As to "overlap" in the bass between the EP500 and M22s, you should note that although Axiom terms the EP500 control a "crossover" it isn't a full crossover which rolls off the sub above the selected number and rolls off the speakers below that number. More accurately it's a low pass filter which rolls off the sub but has no effect on the frequencies fed to the speakers. The M22s continue to get the full bass range to play within their capability. Setting a lower number on the low pass filter(e.g., 60 rather than 80Hz), reduces the overlap in the 60-80 Hz area where the M22s are still strong and can be tried to see if you prefer it.
