At 100 watts or slightly more for each channel, I would expect the Classe to easily drive the 703s to painful levels without breaking a sweat. Have you tried moving them around the room some to see if the room is a little too absorbent? Also verify the polarity of your speakers to make sure they aren't canceling each other out. I would expect both sets of speakers to behave similarly based on there similar efficiencies. They may sound different but they should both play very loudly without distorting. Are all the screws tight on the 703s and no damage to the speakers themselves. I don't know how the speakers are constructed but sometimes the flex ring around the edge deteriorates and the speakers sound terrible.