We need more details. Source, amp, cables, power cords, room size, preferred sound signature and taste of music. Also, how loud you usually listen to.
Room acoustics is always very important, of course. If you decide to go with subs, yes, two subs is almost always preferable but you can start with one.
In my system I can demonstrate how one power cord on the integrated amp adds or subtracts bass, to put other things aside for now. I mean both the bass quality and how low it can go. In other words, everything matters, some things more and some less.
Still, you might find that you have to replace your speakers.
Room acoustics is always very important, of course. If you decide to go with subs, yes, two subs is almost always preferable but you can start with one.
In my system I can demonstrate how one power cord on the integrated amp adds or subtracts bass, to put other things aside for now. I mean both the bass quality and how low it can go. In other words, everything matters, some things more and some less.
Still, you might find that you have to replace your speakers.