The X-250 will give you a more refined sound, better details, dynamics, slam and has extra juice whenever you need it. Once you hear them side by side then you will understand. I am not familiar with your speakers so I do not know the synergy with Pass Labs amps. The key to a good sounding system starts with the synergy with the amp and speakers. The is the first voice you listen to. Then you add the source in my opinion. The EMC-1 is a neutral unit with great soundstage, details and dynamics. The Electro DAC that I tried in my system added those same characteristics to my system for the better. Again, I am not familiar with your speakers so I would take the time to contact some Jean Marie dealers to see how the speakers are voiced and to see if they have had any experience with the Pass amps and the speakers.
Happy Listening.