My first reaction is that the M2s might not be enough speaker for your listening area and seating distance. Any reason not to step up a bit to M3s (still small & discrete) or M22s? I realize this isn't your question, and I can't comment on the EP-400, just curiosity.
I started out with nothing & I've still got most of it left
M60 VP160 QS8 EP350
M22 VP100