I've decided to keep the Nano 300, as my band will have a gig again after a long break, and for such occasions (small audience) the Nano in combination with the db K300 is perfect. Powerful enough to play along with a drummer. For that purpose, a Bose computer speaker subwoofer wouldn't do the job of course.

But yesterday I was able to test the brand-new Bose Companion 50, the subwoofer is indeed only 4.6 kg (10 pounds), and the system sounds fantastic. Would be a great little sub to add to the db K300, but I won't buy it without selling another one of my too many speakers...