I would be looking at a pair of bookshelf speakers and a sealed subwoofer. Their smaller size is much easier to deal with for someone who moves a lot, and you do not at all need full range speakers when you have a quality subwoofer (or two). I would look at a 2.1 package.
For a system with powerful bass, check out an
Hsu 2.1 Ultra 15 package. Good speakers and great subwoofer there, with 50 Hz power option, and no need for a converter.
I would also be looking at a
Ascend CBM170/
Rythmik F12 setup, however I can't tell if
the power is 50 Hz compatible on the sub, you will have to contact Rythmik and ask about that.