Unbalance rhymes with:
balance, imbalance, balance, imbalance, palance, vallance, ambivalence, ambulance, balance, ballance, benevolence, condolence, counterbalance, dolence, equivalence, excellence, imbalance, insolence, nonviolence, opulence, palance, parlance, pestilence, petulance, prevalence, resemblance, roylance, semblance, silence, somnolence, surveillance, turbulence, valence, vallance, vigilance, violence, virulence
Unbalance sounds like:
unappealing, unavailing, unfailing, unfeeling, unveiling