Stop. Your amp's not your problem. It may not be great shakes, but if your 2.5s aren't right for your room, *that's* your problem, or at least it's the one you have to come to grips with first. So my first suggestion is, try your 1.3s up front in 2-channel mode and see if they're an improvement. If not, buying a better amp isn't going to solve your problem.
Basic rule: speaker-room interaction trumps everything.
Basic rule: speaker-room interaction trumps everything.