Instead of switching your speakers, did you consider adding a high quality tweeter to your Solovox ? One of the best tweeters available is the WE replica 597A from Line Magnetics Audio. Coupling to the Solovox can be done very easily and simply through a PIO capacitor (+/- 1 uF) and an extra strip of (A23) cables.
I am sure you would be not only surprised but overwhelmed by the musical result.
I add a link to an article (in German) where Roland Kraft describes the outcome of pairing the Rondo (with at the base the same - or nearly the same - chassis as in the Solovox) with the LM 597A
http://www.fidelity-magazin.de/equip...cs-hochtoener/