They only look like black boxes when they're being used. These are small boxes. Why can't they be put in a cupboard, or sideboard, or wherever until you're wanting to listen to them, then taken out, plugged in, enjoyed at their best, then tidied away when finished..? At worst, make a cardboard, or ceramic, or sculptured 'something' to slide over them, thus hiding them from view, then expose 'em for listening. Scope for 'out of the box' thinking here, I would suggest, so as not to too compromise the acoustic qualities that are the 'raison d'être' of such an investment.
Doubtless there'll be some reason why such an approach doesn't meet criteria , but that's how I'd go about resolving the issue.
Hope this helps.