Sony has a long heritage of building entry-level loudspeakers to match their midi-Hifi systems. There are some really interesting desicions underlying the design philosophy. Manufacturing cost was possibly the greatest priority then followed by playability. Many people would have seen the Sony midi-Hifi in the store and decided that the system looked capable and being Sony, would be a good quality. Turn up the volume, yes nice and loud. Turn up the bass, nice and boomy. The emotional choice has been made.
The Sony SS-H311 loudpeaker is a 2-way ported loudspeaker with 6Ω rated impedance. The power rating is not quoted. The woofer drive is a Sony 4" Woofer (Sony model 1-544-237-21) and what looks like a 1" wide range tweeter. The crossover is possibly around 1.5kHz.