Dared MP-7 Problem

I have been using a Dared MP-7 SE amp with 7 watts in a small system with 88db efficiency speakers. They sound very good just not quite loud enough to fill the room. I just purchased a pair of Cain and Cain Abbys with a 95db efficiency rating. The problem is when I connect the Abbys to this amp the Cats Eye Tube tells me I am overdriving them the minute I hook them up, NO VOLUME. I can also hear a high-pitched oscillation. I can turn the volume up But it sounds like I am over driving them, as the sound seems soft. The abbys seem to work well with my SS equipment. Whats the Problem?