You'll want something that does both voice and rhythm. It's possible. There are tube amps, even reasonably-priced integrateds, that can give you both that lovely, liquid, almost 3-D singer floating in space between your speakers and the speed and timing that will make you have to choose between sitting there glued to the music or dancing around the room.
It's my guess that your system is quite dynamic but a bit flat. Your speakers can do justice to a much better amp, but they would prefer one that has a bit of punch. Taking speakers in to a store so you can listen to an amp is a lot harder than doing it the other way round, but your speakers are the best thing you've mentioned. You haven't said what your source is.
If your significant other is not enthusiastic about a system that makes great music, she may not yet have heard something that really touches her. Female listeners are often humbling to me because they actually seem to hear better. If you want good gear, she may well be able to tell you what's the best.
