The Q201E has a small footprint (only 12 inch square). The "Q" subs are more for the Home Theater crowd, but do have the same connections and are quite musical as well. I have demo'd a Q201E at home; great sub considering how small it is. I use an old Q100E in my separate home theater system.
The other advantage for music with the "ST" Mark III subs is the selectable crossover in exact 2dB increments. The Q subs only have the typical knobs with no indication of the exact crossover frequency.
The other advantage for music with the "ST" Mark III subs is the selectable crossover in exact 2dB increments. The Q subs only have the typical knobs with no indication of the exact crossover frequency.