Your system is well balanced, and I would suspect quite musical. In terms of speakers, either method would achieve greater bass.
However, your room size may indicate a better match for the addition of a sub. This combination would allow greater placement flexibility for the 3 speakers. Subs can be added to extend bass, and complete the sound of an already good sounding system - which I would say yours is. While I am not a big fan of outboard subs, there are some very good "bookshelf" sized speakers that can use the extra help to achieve deep accurate bass. That is what it sound like you want to achieve, and the speakers you have.
Let us know how it sounds!
