The 100s take a lot of power to sound good, and in your dealer's set up the amp should have enough juice for them. I also think the pre amp is a fine one, and wire is satisfatory. Therefore I only have 3 conclusions: 1) the room set up is poor 2) the pre/pro is not configured for the room/speakers 3) you do not like the sound of the 100s. Only suggestions I can offer are ask the dealer to calibrate the pre/pro or take a pair home and try them in your own surroundings which is really the only way to tell if gear will work for you.
Good luck.
Good luck.